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-   -   737-500 missing in Indonesia (https://www.pprune.org/rumours-news/637944-737-500-missing-indonesia.html)

Lookleft 12th Jan 2021 02:59

Its not an extract of the AF447 report but the AF447 accident is listed as the classic example of loss of control where the crew should have been able to handle the problem. I am not sure which incident the extract refers to. Its never too early to speculate but probably it is too early to have any factual information.

VH-MLE 12th Jan 2021 03:05

My apologies for any confusion, the extract referred to another B737 accident (Adam Air) & was not meant to imply AF447. I was just trying to make the point that occasionally accidents occur for reasons that seem hard to fathom...

Judd 12th Jan 2021 04:31

Adam Air was just another of these type of accidents where automation addiction (which is just another way of saying automation dependency) had a hand in these loss of control accidents. They usually have a common denominator. That common denominator is the pilot lacked the basic skill at hand flying without the aid of the flight director. In each case the pilot found himself in an unusual attitude in IMC or at night despite all the flight instruments operating normally - including the flight director. How or why the aircraft got into an unusual attitude or jet upset in the first place can be often traced back to poor instrument scan after engaging the automatics.

There have been accidents where the pilot thought the autopilot was engaged when it wasn't. The aircraft was allowed to slowly drift into a turn which slowly turned into a nose low or nose high situation which only got worse as the pilot attempted to re-engage the automatic pilot instead of first levelling the wings and putting the aircraft into stable flight before attempting to re-engage the automatics.
A classic example of this type of accident is here: https://en.wikipedia.org/wiki/Flash_Airlines_Flight_604

Note in that accident the frantic calls by the captain to his first officer to engage the autopilot when the 737 was already out of control and in an unusual attitude at night soon after takeoff. To put it more crudely the pilot simply did not trust himself to recover on instruments. Hence his urgency for the crutch of the automatic pilot to do the job for him. . Would not this be picked up during scheduled simulator checks? Not necessarily so because the majority of simulator training and checking is conducted with full use of automatics.

is it any wonder therefore that faced with an unusual attitude in IMC or at night, pilots who have become automation dependant (for whatever reason) will often attempt to engage the automatics to help them fly the recovery. Where the unusual attitude has been allowed to become severe, and good basic instrument flying skills are needed to get the aircraft under control, the lack of these basic skills makes the end result inevitable. Because the tight tolerances of modern navigational requirements often limit practice hand flying on line, the key to maintaining hand flying instrument flying skill is practice in the simulator. After all, isn't that what simulators are for? Operators have a flight safety responsibility to schedule time for this practice.

Lookleft 12th Jan 2021 06:08

Does anyone know if this particular 737 would have the older FDR that only recorded 4 parameters or the later model that recorded more (200 I think)?

Janner200 12th Jan 2021 06:11


Thankfully uncontained failures are rare, If it does occur however despite designing to keep critical systems and components outside the burst zone the final outcome is heavily dependant on chance. This is far beyond any certification case and a disc failure can break the engine in 2 which is likely to result in detachment of the fan cowl doors and possibly the reverser C ducts. The front and rear of the engine could still be attached to the airframe but significant damage to the pylon could have occurred. An instantaneous loss of thrust coupled with a drag increase as the nacelle breaks up is possible. Occurring at high rating on climb out would be very hazardous.

tdracer 12th Jan 2021 06:41


No first hand knowledge, but my educated guess is that - based on when it would have been built - it had a higher tech Digital FDR with lots of parameters (the new ones have thousands of parameters).
I'm more concerned with the health of the FDR - it's not exactly unheard of that the FDR isn't working properly at the time of a crash. Checking the proper functions of the FDR (and voice recorders) is not a high priority for the maintenance types, even in the west.

DaveReidUK 12th Jan 2021 06:49


"Another FAA rule change that took effect October 11, 1991, led to the installation of digital FDAUs (DFDAUs) and DFDRs with solid-state memory on all Boeing airplanes before delivery. This FDR system was required to record a minimum of 34 parameter groups. The DFDAU processes approximately 100 different sensor signals per second for transmission to the DFDR, which uses electronics to accommodate data for a 25-hr period."


The accident aircraft was built in 1994.

Dannyboy39 12th Jan 2021 07:07

Originally Posted by tdracer (Post 10966084)
Checking the proper functions of the FDR (and voice recorders) is not a high priority for the maintenance types, even in the west.

Sorry for being a bit facetious, but it's not about priorities - each airline worth their weight in salt will be following guidance from the OEM manufacturer planning document and approved by their national authority in their maintenance programme. Priorities don't come into it.

Asturias56 12th Jan 2021 07:09

BBC reporting black box locator isn't working - new one on it's way from Singapore


Asturias56 12th Jan 2021 07:13


They shouldn't but even in proper First world airlines they do I'm afraid - you can't expect a LCC with a 30 minute turnround to get the same TLC as one that takes 90 minutes on the ground :(

Dannyboy39 12th Jan 2021 07:19

The purpose of the CVR or the FDR is not to download it after every flight and there is no maintenance requirement to do so. There is also a mandate coming with requires 24 hour recording, not just 2 hours. The systems get periodically function tested and the ULBs get replaced every 5-6 years too.

Icarus2001 12th Jan 2021 07:34

FDR and CVR and both MEL approved items, so the point is moot.

arba 12th Jan 2021 08:58

the box is found!

Euclideanplane 12th Jan 2021 10:24

Apparently the FDR, not yet the CVR.

Max Angle 12th Jan 2021 11:28

you can't expect a LCC with a 30 minute turnround to get the same TLC as one that takes 90 minutes on the ground
Short haul airliners whether on the ground for 30 mins or 90 mins receive no TLC during a turnround other than a walk round conducted by the flight crew or sometimes an engineer. In EASA land there is a brief engineering check every couple of days but between that the aircraft could fly 10-15 sectors without ever being looked at by an engineer.

flyfan 12th Jan 2021 12:01

^^ To be precise, every 48h an engineer checks the aircraft.

aterpster 12th Jan 2021 12:40


Flightcrews at my airline preflighted the CVR on the first leg of the day. I don't know about maintenance with the FDR.

DaveReidUK 12th Jan 2021 14:00


The minimum 34 parameter groups:

1. Time or Relative Time Counts
2. Pressure Altitude
3. Indicated airspeed or Calibrated airspeed
4. Heading (Primary flight crew reference)
5. Normal Acceleration (Vertical)
6. Pitch Attitude
7. Roll Attitude
8. Manual Radio Transmitter Keying or CVR/DFDR synchronization reference
9. Thrust/Power on each engine—primary flight crew reference
10. Autopilot Engagement
11. Longitudinal Acceleration
12a. Pitch control(s) position (nonfly-by-wire systems)
12b. Pitch control(s) position (fly-by-wire systems)
13a. Lateral control position(s) (nonfly-by-wire)
13b. Lateral control position(s) (fly-by-wire)
14a. Yaw control position(s) (nonfly-by-wire)
14b. Yaw control position(s) (fly-by-wire)
15. Pitch control surface(s) position
16. Lateral control surface(s) position
17. Yaw control surface(s) position
18. Lateral Acceleration
19. Pitch Trim Surface Position
20. Trailing Edge Flap or Cockpit Control Selection
21. Leading Edge Flap or Cockpit Control Selection
22. Each Thrust reverser Position (or equivalent for propeller airplane)
23. Ground Spoiler Position or Speed Brake Selection
24. Outside Air Temperature or Total Air Temperature
25. Autopilot/Autothrottle/AFCS Mode and Engagement Status
26. Radio Altitude
27. Localizer Deviation, MLS Azimuth, or GPS Lateral Deviation
28. Glideslope Deviation, MLS Elevation, or GPS Vertical Deviation
29. Marker Beacon Passage
30. Master Warning
31. Air/ground sensor (primary airplane system reference nose or main gear)
32. Angle of Attack (If measured directly)
33. Hydraulic Pressure Low, Each System
34. Groundspeed

capngrog 12th Jan 2021 14:20

Would pilot knowledge of the existence of recording of parameters nos. 27 & 28 tend to reduce enthusiasm for hand flying approaches? Would it be outside the realm of practicality for airline management (e.g. chief pilot) to occasionally randomly review such data?

zero/zero 12th Jan 2021 14:48

Most modern airlines already do this... Flight Data Monitoring (FDM). And it's not random, everything is monitored for 'trends'. But that's another discussion altogether

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