Back to home pageEmergency Descent

Home > Pilot Notes > Stories & Articles > Emergency Descent


Illustrated technical information covering Vol 2 Over 800 multi-choice systems questions Close up photos of internal and external components Illustrated history and description of all variants of 737 Databases and reports of all the major 737 accidents & incidents History and Development of the Boeing 737 - MAX General flightdeck views of each generation of 737's Technical presentations of 737 systems by Chris Brady Detailed tech specs of every series of 737 A collection of my favourite photographs that I have taken of or from the 737 Press reports of orders and deliveries Details about 737 production methods A compilation of links to other sites with useful 737 content Study notes and technical information A compilation of links to major 737 news stories with a downloadable archive A quick concise overview of the pages on this site



By John Laming



See more details about the book

All of the information, photographs & schematics from this website and much more is now available in a 374 page printed book or in electronic format.

*** Updated 14 Nov 2021 ***

The 737 Tech Site on Facebook The 737 Tech Site on Twitter The 737 Tech Site on Instagram The 737 Tech Site on Instagram

While on holiday in England in 1980 I met the well-known British author of aviation stories Captain David Beaty. We chatted over tea at his beautiful thatched roof cottage in Sussex and he told me of the background of some of the stories that he had written.

He had been a RAF pilot during World War Two winning the DFC and Bar while flying Lancasters over Germany.


I had read one of his early books called “Call me Captain” which was fiction based on fact of his experiences after the war flying with BOAC. The story was about a bomber pilot having left the RAF and joining a British airline as a first officer. The airline was riddled with class-conscious white-gloved captains who looked down upon new arrivals with disdain. Although an obviously highly experienced and decorated pilot, he was treated like dirt by these snobbish “commanders” who could and did wreck a first officers civilian career if their professional decisions were questioned.


Many years later Beaty’s experience with these characters came to my mind after talking to a young pilot who had just completed an interview with a prestigious Australian airline. Allowed in the cockpit for a return flight to his hometown, he was struck by the cold and formal atmosphere between captain and first officer. Some minutes had passed since he had been invited (at his own request) to the cockpit and not a word had been said. No greeting – no nothing. The first officer was staring gloomily out of his side window and the captain sat rigidly upright staring ahead.

Somewhat embarrassed and feeling like an intruder, the young pilot politely asked “Do you chaps overnight at Melbourne or do you return to Sydney today?” 


The first officer ignored the question and continued to stare outside. The captain turned around and in a flat expressionless voice said, “ For your information we are not ‘You Chaps’.     My name is Captain Smith and I strongly recommend that you learn some respect if you intend to join this airline”..


As it turned out, the young pilot failed the airline interview but in weeks to come he was interviewed by another Australian airline and by Cathay Pacific in Hong Kong. Both airlines offered him a job. He took the Australian airline job and now is within a year of his command on the Boeing 767.


Another fine book by David Beaty was “The Cone of Silence”.  Again it was fiction based on fact that dealt with the circumstances and personalities involved during a series of accidents to the early Comet 1 jet transports operated by BOAC. Two of these accidents were caused by premature rotation during the late part of the take-off run with the result that high drag degraded the acceleration. The tail of the Comets then dragged along the ground and the aircraft never got airborne. A contributory cause of the accidents was lack of adequate flight testing prior to the aircraft going into airline service. The daughter of a Comet captain killed during one of the accidents and after talking to her, Beaty wrote his book around her efforts to clear her father’s name.


At the time of these accidents I had been flying Vampire jet fighters where the recommended take-off technique at the time was to raise the nose-wheel at 80 knots by firm back pressure on the control column, allowing the aircraft to fly itself off the ground around 100 knots. It was a tricky process especially at night when it was easy inadvertently to lift the nose too high during the take-off run and thus allow the aircraft to become airborne in a mushing attitude. As the Comet and Vampire were both manufactured by the De Havilland company, it occurred to me in later years that the nose-wheel-off-the-ground technique had been applied to both aircraft types.

Owners of  “Warbirds” which are civilian versions of old military aircraft sometimes use original Pilots Notes as the only authoritative information available. Because of this there have been instances where the techniques written in the Vampire and Venom manuals have led to exaggerated nose high attitudes during the take-off run and the aircraft have failed to accelerate.   Perhaps the lesson has been learnt because now modern jet transports leave the nosewheel firmly on the ground until rotate speed is reached and the aircraft is flown off the ground.


In 1969 David Beaty wrote his first non-fiction book calling it “The Human Factor”. He told me that while researching accident reports for this book he had talked to current and retired airline captains about their experiences involving pilot error. He was surprised to find that most were reluctant to admit to that they may have made serious errors of judgment or professional skill. Yet Beaty knew from his own experiences as a RAF bomber pilot and later in the airlines, that it is impossible to go through a flying career without making numerous minor errors of judgment and certainly a good deal of major stuff-ups.


As we talked over tea I suggested that should he write a sequel to The Human factor, it may prove fruitful to talk to co-pilots on the subject of what they have seen in the cockpit. My view was that co-pilots are always witness to mistakes by the captain, but that for career promotion reasons tend to keep quiet at what they hear or see. Immediately I sensed that I had overstepped the bounds of British class respectability because our conversation was politely terminated and I was shown the garden gate.

Clearly the redoubtable Captain Beaty had little time for the opinions of co-pilots. It was the idiotic British class snobbery that had plagued their industries in ages past.


Like most experienced pilots, my career included a multitude of questionable decisions most of which had happy endings for my crew and passengers. Some pilots are reluctant to admit mistakes, as David Beaty found out. For example in one company that I flew for the chief pilot was carrying out conversion training on some newly recruited Boeing 737 pilots. The wind was calm and the runway on a Pacific atoll was over 7000 feet long. Rather than do touch and go landings the check captain elected to carry out full stop landings then after doing a 180 at the far end would take off in the opposite direction. After take-off he would instruct the pilot under training to carry out a reversal or dumbbell turn then re-land again. And this was done several times over twenty minutes. Each time the landing gear would be retracted when good airmanship dictated that the gear should be left extended to cool the brakes.


After the training was completed the 737 was taxied to the airport terminal and the brakes parked on. Five minutes later the heat generated by the series of full stop landings and the brake applications required caused the fusible plugs to melt in the wheels and the tyres deflated and the brakes welded on.  This was a clear monumental cock-up by the check pilot. However, as he was also chief pilot he was able to deny responsibility for his actions. He wrote up the defect in the aircraft technical log as a suspect anti-skid unit fault. The flight was delayed 24 hours while awaiting a new set of wheels and brakes to be flown by charter aircraft from the home base 350 miles away. No one talked and the technicians pronounced the anti-skid system serviceable.


Perhaps 90% of pilot errors and potentially serious mistakes are kept within the closed flight deck doors. That situation will not change while status, personal pride and promotion prospects re involved.


                                          Not suffering fools gladly.


I had just returned to flying the 737 after two years absence. The usual course of events after recruitment is to undergo refresher training in the flight simulator followed by en-route training before being cleared to operate as captain. In my case, my return to the company had been somewhat traumatic because of dirty politics that unfortunately seems part of life in aviation at some time or other. I was to be set up for “the treatment” in the simulator by the duty check and training heavy. This involved the first thirty minutes in the simulator being characterized by moderate to severe turbulence at the same time multiple emergencies were introduced. An engine failure at V1 followed by asymmetric leading edge devices as the aircraft climbed away on one engine in turbulence, was not a realistic exercise, but certainly an startling opener to what was euphemistically termed a “training session”.


During this first session of four long hours, the check pilot would resort to bitter sarcasm and foul language at any perceived errors. This man had been a young flying instructor with a Melbourne flying school with a reputation of terrifying hapless student pilots. With increasing rank he had got worse and became a feared “career-buster”. He lacked any patience and despite an affable manner in the bar he turned into a real Jekyl and Hide character in the cockpit.


One of the simulator sessions with him included a simulated rapid loss of cabin pressure followed by an emergency descent. It is assumed that a window has blown out and the crew has to get the aircraft to lower levels where oxygen masks are not required. In real life, an explosive decompression would be noisy and alarming with possible severe ear pains. While the instrument indications and noise can be faithfully reproduced in the simulator exercise, obviously ear pain cannot. That is unless the constant ear-bashing by this check captain could be called “prolonged ear distress”.


Following the first instrument indications of an explosive decompression, various cockpit checks are followed in order to trouble-shoot the problem and get the pressurization under control. Meanwhile, the crew dons oxygen masks and in the cabin more masks drop from the ceiling for the passengers. If the crew are unable to rectify the problem, then a rapid descent to lower altitudes are carried out. During this exercise in the simulator we would be set upon by this clown of a check pilot who would get himself wound up in anger at any perceived tardiness in our crew actions. During one emergency descent from 35,000 feet this instructor froze the simulator for one minute to deliver an earful of unwarranted abuse to myself and another captain then allowed us to continue diving the aircraft to 10,000 feet. We were forced to take this abuse on the chin less the dreaded tick was placed in the fail on our records. 


A simulator session with him was invariably a stressful and unpleasant experience. Records had to be completed, boxes ticked, and a four hour session involved a series of engine failures, aborted take-offs, mysterious failures of yaw dampers, vertical gyros, automatic pilot channels, hydraulic failures and even pilot incapacitation. Any thoughtful delay in decision making would be the sign for vitriolic tantrums from this particular check pilot. But there was occasional humour – albeit it inadvertent.


A captain and first officer were undergoing “the treatment” with the target being an outspoken Australian first officer who had riled the instructor. The captain sitting in the left seat of the 737 simulator was privately briefed by the instructor to simulate a heart attack during the take-off. In theory the ever-alert first officer would calmly  take control and save the day. The first officer was blissfully unaware of the plot that was to take place near V1 decision speed on the take-off run. Unseen by the first officer the instructor would tap the captain on the shoulder as the aircraft approached V1 and on cue the captain would collapse over the controls. The first officer would then take over, either applying the brakes to pull up on the runway or he would fly the aircraft off the ground.


The first officer was a highly experienced and well-mannered individual who had flown bombers in the RAF before joining this company as a 737 first officer. The captain had learned to fly at an aero club and had built up seniority through sheer time in the company rather than any exceptional ability. There had been unspoken friction between the captain and the first officer who had difficulty accepting the rather superior attitude of the captain.  He also had little time for the check captain instructor whom he dismissed as a rude bore.  Thus the scene was set for drama in the simulator as the 737 approached V1.


On being given the nod by the instructor, the captain gave an almighty groan and collapsed in his seat apparently unconscious. Startled, the first officer looked at the slumped captain and anxiously inquired if he was OK. He genuinely thought the captain (who had been known to enjoy a wee dram) was having a real heart attack. Meanwhile, the 737 accelerating down the runway under full take-off power began to drift off the runway due to a cross-wind. The first officer looked despairingly back at the simulator instructor and called him to get a doctor as he thought the captain had suffered a heart attack and was probably at this moment dead. The 737 was now heading flat chat across the aerodrome toward the airport terminal which was realistically portrayed on the front windscreen. The instructor lost his cool and snarled at the first officer to “do something for fuck’s sake”.  Too late, the 737 disappeared into the virtual reality of the airport terminal no doubt wiping out hundreds of happy holidaymakers in a gigantic explosion of World Trade Centre enormity.


It was then that the first officer realized that all this was a pre-planned exercise called Pilot Incapacitation and prepared himself for the inevitable torrent of abuse from the instructor. He was not to be disappointed and managed to hold his own anger in check while the instructor frothed and the captain calmly gazed out of his own side window without offering any comment. The fake heart attack was indeed a magnificent piece of acting by the captain but he received no accolades from either instructor or first officer. In the box for pilot incapacitation, the instructor ticked Fail.


The first officer suggested that the sequence should be re-run now that he knew what was expected of him. The element of surprise was obviously gone, and his request was curtly refused. At the coffee break a few minutes later, the instructor accused the first officer of being a smart-arse and hinted darkly that his promotion prospects to a command were dim. Meanwhile, the next half of the session commenced with the first officer at the controls and the captain acting as his assistant – known as PNF or Pilot –Not-Flying.


Opening up to full power the first officer commenced the take-off run. Just before lift off, he gave a strangled cry and appeared to collapse in agony over the controls. This was not a pre-briefed exercise and both the captain and the instructor acted in unison to restrain the first officer who was coughing feebly and waving his arms aimlessly. Meanwhile the 737 with no one at the controls once more headed for the airport terminal at ever increasing speed. The first officer suddenly woke up and shouted “Fuck” as the aircraft disappeared into the terminal building in an identical scenario to the last one. Lightning had struck the happy holidaymakers twice in one day! 


With a beaming smile, the first officer turned to the captain and said “You stuffed the incapacitation exercise, captain.  Now we are quits”…

The instructor then berated the first officer for having an un-briefed, un-authorized heart attack and in the first officer’s personal records annotated that this man had an attitude problem which would seriously affect any future prospects for promotion.

The first officer eventually saw the writing on the wall and resigned to take up a 737 command in the United Kingdom. I find it curious that in all simulator sessions that I have witnessed where pilot incapacitation drill is practiced, the sequence always calls for the captain to die, leaving the first officer to take over control and land the aircraft.


When I queried this apparent anomaly with a senior airline check captain he brushed off the question by saying that the “test” was to see if the junior pilot could take over control without crashing the aircraft. I pointed out that if the incapacitation of either pilot took place at a critical point on take off or landing, quick thinking would be required by any surviving crew member. Therefore, it would seem logical that both captains and first officers should be given the opportunity in the simulator to practice taking over control if either collapsed. The senior check captain lifted an eyebrow at my daring to question a long-standing policy that only the captain has a heart attack in the simulator and therefore there is no point in testing his reactions. What dangerous nonsense..


I sometimes ponder the varied methods that airlines use to sort the wheat from the chaff when recruiting pilots. At the flying club bars, interesting stories emerge of batteries of complicated aptitude tests, followed by deep and meaningful questions by airline physiologists. One day I was flying a Boeing 737 from Hamburg to Seville in Spain. The first officer was a delightful fellow that had apparently failed to get into Lufthansa German airline but was now very happy to have a job with Hapag-Lloyd. I was then on contract to Hapag-Lloyd as a direct-entry British captain. The first officer told me that he had bombed out on the Lufthansa aptitude tests. These included prospective recruits to “fly”a bouncing ball on a computer screen while simultaneously inputting a series of numbers into a keyboard. During this process, the supervisor would ask the recruit to multiply 24 by 21 or similar mathematical calculations of mental arithmetic. All this nonsense to be a first officer on a 737. It seems that at least as far as some airline policy is concerned computer skills are more important than pure flying ability. Such is the way of “glass cockpit” technology where automation is in and hand-flying skills are out.


Contrast these aptitude tests to be a first officer to the selection of check captains. Batteries of aptitude tests to check personality traits? Not in my experience in the airline industry.  Demonstrated skills at pattering a manual reversion following a complete hydraulic failure or pattering a one-engine inoperative DME arc? Again, no way are these hands-on skills demanded of a prospective check captain. Demonstrated ability to laugh at the chief pilot’s jokes at the bar and mix socially with the company’s A team?  Now you’re getting warm.


I could count on one hand the number of really first class check captains and simulator instructors that I have flown with in my career. They are characterized by the same admirable traits of patience, understanding and the ability to bring out the best of each pilot that they fly with. In short, they were all gentlemen.  I learnt little from the rest except perhaps how not to instruct.


The foregoing paragraphs could be entitled “And other Stories” as part of the original title of this article. Let me now describe how misplaced emphasis on instant decision making was partially to blame for an unusual series of events during a night flight over the Paciific. This story is called;  


                                        On Emergency Descent


The Boeing 737 flight to Rarotonga in the Cook Islands was scheduled to depart its island base at 0100 local time. Flight plan time was four hours with initial cruise at 33,000 feet. The crew consisted of a maintenance engineer, four flight attendants, the first officer, and myself as captain. There were 24 passengers including an 80-year-old Polynesian lady on her first flight. The aircraft had just previously flown in from Australia and the crew had gone to bed at the local hotel. There were no reported defects logged in the technical log.


It was a black night as we taxied for take-off. The first officer and I had tossed a coin on who should fly the leg and he won. As he was an experienced pilot with excellent instrument flying ability, I had no qualms about losing he toss. In any case if some unusual event took place I would take control while the first officer would revert to back up and monitoring duties.  Climbing through 23,000 feet the aircraft picked up light icing and we switched on the anti-icing system. This would bleed hot compressor air from the engines to piping surrounding the engine inlet cowls.  Failure to do this could eventually cause ice build up to break into chunks and be ingested by the engine. In turn, a flameout and engine damage was likely. The other side of the coin was that fuel consumption was significantly increased while anti-ice heating was operating and this could eat into our reserve fuel at the destination.


It was company policy for the crew to monitor the worldwide emergency radio VHF frequency of 121.5 khz while en-route. Our route was initially outside of controlled airspace until reaching the Nandi (Fiji) Oceanic Control Area about one hour after take-off. Hardly had we switched to the emergency frequency when we heard a Qantas flight calling on 121.5 that he was about to climb from 31,000 to 33,000 feet. The reception was crystal clear and obviously the aircraft was not far away. We acknowledged his call with out own position and altitude, and it turned out that his track to Honolulu lay across ours at 90 degrees. There was no immediate risk of a collision but if we had departed a few minutes earlier it might have been perilously close. The local Flight Service Officer had failed to check his teleprinter to see if there had been warning of conflicting traffic, although the Qantas aircraft had wisely broadcast his own intentions on the emergency frequency. The safety net worked that night.


The first officer and I were still discussing the separation problem when a warning horn sounded in the cockpit. Outside, the night was black, the red and green navigation lights on the wing tips reflecting off thick cloud accompanied by the flashing of the strobe lights. Having read somewhere that reflection of strobes from cloud at night can cause epileptic fits, I switched them off. It then dawned on me that the warning horn with its intermittent sound was the cabin altitude alert system. A quick check showed the pressurization system was playing up and that the aircraft was slowly depressurizing. This was potentially serious and requiring the immediate donning of our oxygen masks. The cabin pressure should have been equal to 8000 feet which is normal in most jet airliners for the altitude that we were flying 31,000 feet. The cabin altitude gauge showed 12,000 feet and steadily increasing.


The Boeing checklist calls for both pilots to don their oxygen masks and when that it done and the life-saving oxygen is flowing, various switches are moved in order to try and get the cabin pressure under control. At 14,000 feet cabin altitude, the passenger oxygen masks automatically release from panels over each row of seats so that passengers can put them to their face and breath oxygen. If the crew cannot control the loss of cabin pressure, the captain then puts the aircraft into a high rate of descent until around 10,000 feet where ample oxygen exists.


Unfortunately, in the haste to don my oxygen mask I knocked my glasses to the floor making it difficult to immediately focus on the instrument panel. It was then that I made the wrong judgement call. Rather than wait and investigate the cause of the pressurization failure before deciding to get the aircraft down to lower levels, I made the decision to get going down right now. The first officer transmitted a radio call to anyone on our frequency that we were commencing an emergency descent, while I warned the flight attendants, extended the speed brake closed the thrust levers to idle power and gently eased the 737 into a high speed dive.


This was just like the scenario posed in the simulator training exercises, except for the extremely painful pressure build up in my ears. As we plummeted down through thick cloud at close to 6000 feet per minute I handed control to the first officer in order to retrieve my glasses which were in the dark near my feet. That done, I could focus on the pressurization gauges and was surprised to see that the cabin pressure had been brought under control by the efforts of the first officer. The immediate emergency was over and after leveling the aircraft at 20,000 feet, I engaged the automatic pilot, checked the radar for storms ahead, and asked for a situation report from the cabin crew.


Apart from a few sore ears, everyone was OK. I discussed a plan of action with the first officer and it was clear that it would be folly to continue the four-hour flight to Rarotonga with the possibility that a latent fault in the pressurization system could crop up again. Fortunately the first officer had got the pressurization under control before the passenger oxygen masks had dropped, and I decided to return to Nauru, our departure point. After an uneventful landing, I told the passengers to wait in the airport lounge until engineers could rectify the pressurization fault. As they filed from the aircraft, the little old lady who was on her first flight touched a young island stewardess and said "That was quick, my dear – are we at Rarotonga already?” 

Clearly she had no idea of the drama that had taken place over the past thirty minutes, and presumed that a 737 barreling down at 340 knots at night at 6000 feet per minute was a normal flight procedure.


It was then discovered that the cause of the problem was a faulty pressurization controller that had been installed by an engineer when the aircraft had arrived from Australia a few hours earlier. The crew on that flight had noticed a fluctuating pressure in the cabin which was causing discomfort to the passengers. On arrival, the controller was replaced with a spare that was held in a spares box in the cargo hold. The plastic bag in which the replacement controller had been kept, was full of moisture some of which had seeped into the controllers black box. The technical log had been correctly filled with details of the changeover, but this had been on the last page of the log. A new log-book had been given for me to sign but the old log book had not been available for me to check on past defects.


Once airborne and climbing through the freezing levels of 15,000 feet or higher, the moisture in the replacement cabin pressurization controller had frozen causing it to fail. Our engineer put yet another controller in place and we departed for Rarotonga a few hours late. We saw the sunrise over the Ellis Islands (now the Republic of Tuvalu) and landed in time for lunch at Rarotonga. The little old lady trotted off the aircraft after what was to her a boring flight with no emergency descent to liven things up, and I watched with affection as her grandchildren kissed and garlanded her with flowers. Now she had a real story to tell her grandchildren.


Back on Nauru a few days later, it did not take long for the knives to come out. There were a few good lessons to be learnt from the incident, but these were lost in the inevitable bouts of recriminations. Playing over the event in my mind, I knew that I had acted too hastily to get the aircraft into an emergency descent. While it was a safe outcome, the method was untidy. The Boeing manual had advised that an emergency descent should not be rushed and that it was better to try and get the pressurization under control first. If that was not possible then a calm unhurried descent could be carried out. In retrospect we need not have had to descend at all. The first officer was in the process of getting the pressurization under control when I had decided to short cut and assume that control of the cabin pressure would not occur.


In defending myself against the criticism leveled at me by the management pilots, I explained that at no time in the simulator were crews given the opportunity to discuss a slow depressurization scenario – which is what occurred on our flight. The simulator instructor would need to tick the box called Rapid Depressurization and so he would test our reactions on that particular training sequence. There would be a huge noise which simulated a massive depressurization caused by a window blowout and all hell would break lose in the cockpit. Within 30 seconds of the emergency being initiated by the instructor, the crew would have the aircraft diving at high speed while snorting noisily through oxygen masks, communicating with the cabin staff, talking on the radio to Air traffic Control and furiously pressing computer buttons. All this made more dramatic by a screaming skull instructor cursing at the crew for perceived tardiness in getting cockpit checks completed and read out. I have seen this scenario countless times in my career and so have my colleagues.


My reaction to the problem that occurred on that flight to Rarotonga was identical to the same ticked box sequence in the flight simulator but with the benefit of hindsight, there is no doubt in my mind that I would have run the whole show differently. The management “A” Team ignored the valuable lessons learned and at the time I left the airline to fly in happier skies, the simulator training sequence remained unchanged.




26 November 2001. 

Footer block