FMC UPDATE 10.7

The last update to this page was: New photos on 07 Jul 2008.

CONTENTS

At long last FMC update 10.7 is available and hopefully we can start using VNAV with confidence again!

Here is a list of its features as listed in SB-737-34-1918, 27 March 2007. Remember some of these features are optional and may not reflect the configuration of your airline.

Note: a full list of features contained in all FMC updates is available in the book.

All of the information, photographs & schematics from this website and much more is now available in a 370 page, 8.5" x 11" book available here.

Version 10.7 upgrade of the FMC software includes these basic changes:

1. Fly-by Hold Entries and Exits

Version U10.7 of the FMC OPS calculates fly-by hold entries and exits that are available when the path geometry is permitted. Before U10.7, only fly over entries and exits were calculated. When the hold pattern is set, the airplane will over-fly the fix on all circuits of the holding pattern until it exits. Fly-by hold entry and exit gives better Required Navigation Performance (RNP) in U10.7. The airplane can stay on the holding side of the hold course.

2. Lateral Steering Overshoot Enhancements

Operators sent reports of "S-turns" that were controlled by the Lateral Navigation (LNAV) without pilot input. This occurs at airspeeds of less than 200 knots groundspeed when trying to lock on and hold the lateral path. Changes to the LNAV control laws in FMC U10.7 will make it more stable at low speeds. The output in U10.7 for LNAV roll command makes better changes between path segments.

3. UNABLE REQD NAV PERF-RNP Message Revision

FMC U10.7 includes two changes to the UNABLE REQD NAV PERF-RNP message.

First, the message will be a caution level for all flight phases. As a result, the UNABLE REQD NAV PERF-RNP message will show on the Navigation Display (ND) when the Actual Navigation Performance (ANP) is more than the RNP.

Second, FMC version U10.7 changes the default RNP alert times. FMC U10.7 also lets the OPC software make changes to the RNP alert times.

4. Vertical Deviation Displayed in all Descent Phases

Before FMC U10.7, the vertical deviation (VDEV) was not shown in the descent modes if the airplane was upstream of the calculated top of descent waypoint.

With U10.7, the Path Pointer for Vertical Navigation (VNAV) and Deviation Scale on the ND are shown in all descent phases and at the start of the descent modes.

5. Revised Lateral ANP Calculation

Before FMC version U10.7, the left FMC and the right FMC could give different ANP values. This was caused when the two FMCs start to calculate the ANP at different times with different position data. Operators have sent reports that landings were aborted in low RNP approaches because of the ANP differences.

In FMC U10.7, the two FMC's will continue to calculate values independently for ANP. The two FMCs will compare their calculated ANP values and the larger value will show on the display.

6. Revised Vertical ANP Calculation

The vertical ANP that was calculated in FMC U10.6 with data that could have been too conservative. Some in-service vertical RNP alerts could have been the result of how vertical ANP was calculated.

With FMC U10.7, the ANP is calculated with Mach to get a more accurate ANP. Analysis shows that the result of the new formula to calculate ANP is that vertical RNP alerts for operations at vertical RNP of 200 feet or less have gone down.

7. Waypoint Speed Constraint Enhancements

The FMC versions through U10.6 showed speed limits on the LEGS page as "AT or BELOW". The Air Traffic Control (ATC) gives a speed and the airplane must keep that speed. The FMC could only make sure that the airplane did not go more than that speed. VNAV holds the applicable speed for the vertical path and makes sure that it is not more than the limit set for the route. The flight crew had two alternatives to hold the speed (with the autothrottle on). It could use Speed Intervention, if that optional feature was enabled, or disconnect the autothrottle and keep the speed manually.

FMC U10.7 lets a flight crew record a waypoint speed limit as "AT" (with no suffix), "AT-or-BELOW" ("B" suffix), or "AT-or-ABOVE" ("A" suffix). An "AT" speed limit is important to VNAV operations. It is most important in the terminal area. This feature will decrease the number of times that flight crews go above the ATC speed limits. Navigation Data Bases (NDB) do not give the "AT", "AT-or-BELOW", or "AT-or-ABOVE" qualifier for waypoint speed limits.

When these qualifiers are included in the NDB, FMC U10.7 will use the waypoint speed limit. When the qualifier is not specified, FMC U10.7 will see the waypoint speed limit as an "AT" limit.

8. VERIFY POSITION Message Enhancements

In FMC U10.6 and previous versions, the VERIFY POSITION scratchpad message told the crew of position data that did not agree. After the message displays, the flight crew identified the best source of position data and then made a decision about the applicable procedure.

The VERIFY POSITION message set is expanded in version U10.7 of the FMC OPS. The identity of the position source that disagrees is shown on the display. The message changes help the flight crew identify the unreliable position source. This helps to decrease the flight crew workload. The new messages are better for RNP operations because the decision of the applicable procedure is easier for the flight crew when they know the error source.

9. RTA Accuracy Improvement

The Required Time of Arrival (RTA) was designed for enroute operations. RTA is a part of FMC U10.6 and previous FMC versions. RTA is intended to correct for differences between Estimated Time of Arrival (ETA) and RTA when the aircraft is approximately two hours from the RTA location.

FMC U10.7 improves RTA accuracy by modifying the method and frequency of ETA updates, which provides better control to the RTA time in dynamic conditions such as winds and when in descent.

10. Geometric Path Descent:

FMC U10.7 and FMC U10.6 use calculated gradients to give the Geometric Path Descent. This is done for the full descent profile when the FULL mode is selected. The FULL mode is shown in the PERF FACTORS page on LSK 1L (GEO DES). The FULL mode is the default mode and cannot be changed to the APP mode unless the Loadable Defaults Data Base (LDDB) is programmed to allow the APP mode.

With FMC U10.7, the LDDB can be programmed to select APP as the default mode. The APP mode uses calculated gradients only during approach and approach transition legs. Cold weather corrections for VNAV path construction are held during approach or approach transition phases. The APP mode uses a "stay high then dive" VNAV descent before approach or approach transition. Operators sent reports that U10.6 had a less than desired speed descent.

This will help with that problem.

NOTE: The LDDB is an operator option that is supplied by Smiths Aerospace. To select APP as the default mode, operators must contact Smiths Aerospace to get a modification to their LDDB.

11. LOC Update Inhibit

Customers report that with FMC U10.6, an update to the localizer (LOC) can cause a lack of precision in the FMC position. This occurs when the localizer path is unreliable or the localizer course in the NDB is not accurate. Many facilities record localizer courses in 1.0 degree increments but updates in 0.1 degree increments are necessary for accurate FMC positions. As a result of this difference, the FMC position can be off.

A logic change in FMC U10.7 will let LOC be disabled when the Global Position System (GPS) position receives an update. A prompt on the NAV OPTIONS page (4R - LOC UPDATE) will let the LOC update be manually enabled or disabled.

The standard condition of the LOC UPDATE prompt is ON. The standard condition lets the same procedures be used for airplanes with GPS as airplanes without GPS.

Version U10.7 FMC OPS has these new basic features:

1. GPS Loss Alerting

Two new messages at the alert level tell the flight crew when GPS data is not available for FMC position updates. When GPS data is not received by an FMC, a scratchpad message is displayed. The message indicates that position data is not available to the GPS-L or the GPS-R.

These messages are an indication that there is a fault in the GPS system or that there is no data available. Data is not available if there is a problem with a GPS satellite system or the airplane is parked in a hangar and cannot receive satellite signals.

This is the text of the new scratchpad messages:

1) GPS-L INVALID

2) GPS-R INVALID

When the airplane is on the ground, the FMC displays the INVALID message after approximately ten minutes with no valid GPS data. When the airplane is in the air, the FMC displays the message about 30 seconds without valid GPS data. The FMC continues to monitor the GPS data after the display of the Loss Alert message. The message is cleared after valid GPS data is received.

The notification of loss of GPS position data, and possible decreased navigational precision supports the RNP procedures.

2. Leading Edge Device for Target Speed Limiting

FMC U10.7 changes the limit on the FMC target speed to 230 kts or less, unless the leading edge flaps are fully retracted. This change is to help make sure that the airplane will not accidentally go above the flap placard speed.

This feature requires CDS Block Point 06 and Autopilot P4.0.

3. VNAV Armed Before Takeoff

Version U10.7 of the FMC lets the flight crew arm VNAV before takeoff. An equivalent feature is available on 747-400 and 777. VNAV automatically engages at 400 feet above ground level (AGL) if it is armed before the start of the takeoff roll. The VNAV speed target is 20 knots more than the last value set on the Mode Control Panel (MCP), until the airplane gets to the Acceleration Height. In version U10.7, the engine out VNAV speed target is calculated the same as the Flight Control Computer calculates for the takeoff mode speed. The Acceleration Height for normal and engine-out conditions is 1000 feet, but can be temporarily changed by the flight crew.

This feature requires CDS Block Point 06 and Autopilot P4.0.

Version 10.7 upgrade of the FMC software has support for this optional feature:

1. Available Option 3461C739A01, "Flight Management Computer System (FMCS) - Takeoff Thrust

Automatic Selection - Enable"

The above Available Option enables the FMC to automatically select an appropriate Takeoff Thrust Rating based on Airline policy. Airport and runway data can be manually entered by the flight crew or data linked to the FMC via ACARS. FMC Operational Program Configuration (OPC) software is used to activate this feature. FMC U10.7 is required. 

The Airline Policy parameters are included in the Loadable Defaults Data Base (LDDB). 

Smiths Aerospace provides the customized LDDB that is installed after airplane delivery.

At the present time, no committed program has been established for U10.8. However it is anticipated the U10.8 software will be available no earlier then late 2008.