Dear fellow simmers,

 

A couple of months ago an Airbus returned to Amsterdam after shutting down one engine during low visibility conditions (RVR 200-400 meters). I wondered if this also possible with the 737NGX, since it requires a single engine autoland. According to the manual this is possible on fail operational airplanes.

 

The FCOM states (4.20.20 / Automatic Flight – System Description – Single Engine Landing):

If an engine fails and the APU is not used to provide a second electrical source, NO AUTOLAND is annunciated and autoland with rollout is prohibited. If an engine fails and the APU is used to provide a second electrical source prior to engagement of the second autopilot, a fail-passive autoland (LAND 2) with rollout may be flown. LAND 3 will be displayed, but fail-passive minimums must be used.

 

The FCTM contains a table (5.27 / Approach and Missed Approach - Fail Passive vs. Fail Operational Autoflight System – Approach and Go-Around – One Engine Inoperative) that states in the FAIL OPERATIONAL column and GENERAL row:

Dual A/P required for autoland.

Autoland (performance permitting) authorized for flaps 30 only.

Use of A/T recommended for autoland. Connect A/T after LAND 3 or LAND 2 annunciates.

 

However, I am unable to engage the A/T and I do not understand why. I am using the APU as a second electrical source, but I am unable to engage the A/T both before and after LAND3 is annunciated and FLARE and ROLLOUT are armed. After setting the A/T switch on the MCP to ARM it immediately releases to OFF. When I restart the engine I am able to engage the A/T.

 

Are single engine autolands simulated in the NGX? And if so, has anybody been able to complete a single engine autoland with the A/T engaged?

 

Kind regards,

Joni Radelaar

The A/T system uses a hardware and a software monitor. If these monitors finds a problem, the system disengages. The engage logic disengages the A/T if one of these conditions occur:

 

* An invalid sensor or A/T system condition

* Airplane on the ground after the flight is complete

* Disengage signal from a disengage switch.

The hardware monitor compares the TRAs for a thrust lever split condition. If both autopilots are in autoland and the A/T rapidly commands a difference of 10 degrees between the two thrust levers, the A/T disengages. This 10 degree difference is from the steady state thrust lever split value.

The A/T permits a steady state split angle to let you operate with engine intermix.

The software monitor disconnects the A/T if it senses a problem with the A/T, thrust lever split, or with the sensors. It also automatically disconnects the A/T when the airplane makes a landing. The software monitor does a check of the TRAs and engine thrust from the EEC for thrust lever split. A rapid A/T command which produces a 10 degree difference between the two thrust levers disengages the A/T. thrust differential of 2,000 pounds also disconnects the A/T.

So when a engine fail's it's senses a thrust differential and a Thurst lever split between both engine, So you are not able to engage the A/T system with one engine running. You can make a autoland but not with the A/T system engaged.

 

 

 

 

 

 

Correct :-) But for example my company's SOP states in case of a engine failure you shall disingage A/P and fly manuel. And in case of very bad viz/weather, then divert single engine vise to another more suitable airport. :-)

Correct :-) But for example my company's SOP states in case of a engine failure you shall disingage A/P and fly manuel. And in case of very bad viz/weather, then divert single engine vise to another more suitable airport. :-)

 

I have come across a fair few airline airline SOPS that make no sense, normally a knee jerk reaction to a one off incident within the airline.

 

Why fly manual and not use a tool that will greatly reduce pilot workload when needed most? Twins are perfectly capable of flying single engine with the A/P in.

 

Regards

 

 

I have come across a fair few airline airline SOPS that make no sense, normally a knee jerk reaction to a one off incident within the airline.

 

Why fly manual and not use a tool that will greatly reduce pilot workload when needed most? Twins are perfectly capable of flying single engine with the A/P in.

 

Regards

 

Hi! Beats me, I have also thought about this, but they have made some funny decisions. And yes it would help to do it with the a/p engaged. Maybe there is a smart thinking behind this or lack of same. ;-P But I just lean against what the SOP says. :-)

 

Regards :-)

Thanks for the replies and explanation!

 

(...)

 

So when a engine fail's it's senses a thrust differential and a Thurst lever split between both engine, So you are not able to engage the A/T system with one engine running. You can make a autoland but not with the A/T system engaged.

 

Could it be that this is only the case for fail passive airplanes? Since if I understand the FCOM and FCTM correctly single engine autolands with the A/T engaged should be possible on fail operational airplanes, provided that the A/T is engaged after LAND 3 / 2 is annunciated.

FLEX1978[/color]' timestamp='1335513597' post='2352686']

Why fly manual and not use a tool that will greatly reduce pilot workload when needed most? Twins are perfectly capable of flying single engine with the A/P in

 

That's a pretty broad generalization that ALL twins have autopilot systems capable of handling the degraded flying condition.

 

Not every plane is the same. Not every airline operating the same plane has the same equipment installed. I think it's safe to say that the training department that is in charge of generating these procedures for the airline understand that the automation can be of great help during an abnormal situation. If it's true that they know that, then it should be safe to assume that they prohibit autopilot use at those times for a good reason.

Of course I am not talking about every twin out there. Considering this is the NG forum I would have thought it was obvious that I am referring to the major twin engined aircraft, eg A320, 737NG, 767, 777

 

All of those aircraft will happily fly and autoland with the loss of an engine.

 

Most SOPS will dictate getting the automatics in as soon as possible in an engine out situation to reduce workload.

 

If his SOP is to hand fly then so be it, it's not dangerous however I see no reason to make it mandatory.

 

Trim out the dead engine get the automatics on

to allow you to fully monitor the situation as PF, then handfly the approach. What's wrong with that?

 

Just my opinion, I'm not losing sleep over it.

Cheers

Rob,

 

Neither am I. Nice to see "cooler heads" here from time to time. :-)

 

I agree with you, and that's generally how we do it at my company. It just comes down to specifics. You'd have to ask that particular company what the reasoning is. I know it's not a helpful answer, but really that's about all there is. I wanted to point out that it is conceivable that a company's specific configuration of an aircraft, or an aircraft's little-known handling characteristics might drive such a mandate to hand-fly.