PDA

View Full Version : CAT II vs Engine Failure


sixfeetabove
10th Jun 2008, 16:09
I have learnt about different philosophies on how to handle an engine failure on a CAT II approach.

Our SOP asks us to complete all memory items for an engine fire by 1000 ft AGL. It tells us precisely that for any instrument failures, warning flags, etc (obviously) below 800 AGL you have to initiate a missed. But for a "simple" engine failure I can not find a straight answer.

My thinking is that I would rather continue for landing, would I have passed 1000 AGL or so and an engine would fail. Why? Because by then you are fully configured, C/L completed, and the plane should be nicely trimmed already. And for the plane I fly the flap setting for single engine approaches is the same as for normal approaches.

But lets say you would initiate a go around, following a engine failure. You would more or less suddenly have full power on one engine and none on the other. Ergo a complete re-trimming of your plane would be necessary. More stress than just pushing the rudder a bit...

Well, what is your opinion?

411A
10th Jun 2008, 17:07
Continue and land, if at all possible.

RAT 5
10th Jun 2008, 17:18
You wont know "if at all possible" until you try. I'm not being smart, but that is a trite answer.

Much may depend on your type a/c. Is it a 2 engine a/c? CAT 2 manual land or autoland. Is your autopilot fail passive/operational? If autoland, is the SE flap setting approved?

More info and perhaps we can help.

411A
10th Jun 2008, 20:40
Sometimes, RAT5, a few folks make it more complicated that it really needs to be.:ugh:

SNS3Guppy
10th Jun 2008, 21:54
Our SOP asks us to complete all memory items for an engine fire by 1000 ft AGL. It tells us precisely that for any instrument failures, warning flags, etc (obviously) below 800 AGL you have to initiate a missed. But for a "simple" engine failure I can not find a straight answer.


Your question raises more questions. You say your Standard Operating Procedures dictate what you should do, but you are saying that you don't know what to do regarding an engine failure during an approach? I find this very hard to believe. Perhaps you meant something else.

When flying an approach, regardless of the minimums, if you have the means and are able to safely continue and land, then do so. If you have a problem which calls into question the safety of the flight, then going missed is most likely your answer.

You indicate any instrument failures, but clearly during an approach to minimums a failure of the clock on a precision approach would not constitute cause to go around. Failure of the clock during an approach in which the timing is the sole means of determining the missed approach point may be another matter entirely. If you've briefed an ILS but lose the glideslope, you're far better off going missed and rebriefing for the localizer-only procedure, but that's also subjective.

If you lose an engine during the approach and that's your only problem, then continuing the approach is appropriate. Do you not have an engine failure during approach checklist?

sixfeetabove
11th Jun 2008, 14:49
Thank you for the answers!

2 Engine Aircraft, no autoland, 2 axis autopilot

Your question raises more questions. You say your Standard Operating Procedures dictate what you should do, but you are saying that you don't know what to do regarding an engine failure during an approach? I find this very hard to believe.

Our SOP does tell us! But, it dictates us only that for any abnormality all C/L items must be completed prior 800 AGL.

No problem if you just passed the FAF, if you are in landing config, fully established - you have time to run a quick C/L and get things sorted before 800 AGL.

But the question is what if the engine fails after 800 AGL...? In your answers I can read that you would continue. That is also what I think would be best.

You indicate any instrument failures, but clearly during an approach to minimums a failure of the clock on a precision approach would not constitute cause to go around. Failure of the clock during an approach in which the timing is the sole means of determining the missed approach point may be another matter entirely. If you've briefed an ILS but lose the glideslope, you're far better off going missed and rebriefing for the localizer-only procedure, but that's also subjective.

That is clear to me.

If you lose an engine during the approach and that's your only problem, then continuing the approach is appropriate. Do you not have an engine failure during approach checklist?

Yes we do, it directs that the appr may be continued provided the C/L can be accomplished prior to 800 AGL.

wileydog3
11th Jun 2008, 15:31
seems like 3 scenarios...

You didn't mention the airplane but with the loss of an engine, you will lose that source of electrical power and then what happens to one of your autopilots. Do you lose one autopilot? If your CAT II procedures are predicated on two autopilots, you are committed to a go-around.

IF it is just a Cat I approach, our procedure on the 737 was to retract flaps to flaps 15 and continue the approach.

IF the failure occurs before 800ft, one argument would be to sort it out before attempting the approach. Below 800ft, just retract flaps and continue.

But other circumstances would influence the decision such as airfield, runway, terrain (approach and go-around), etc.

Good topic for discussion...

FlightDetent
11th Jun 2008, 20:43
Sometimes, RAT5, a few folks make it more complicated that it really needs to be.:ugh:
No they dont.

Once the Lockheed got almost exitnct, I believe the original poster is left with 737. From my memory of the classics, first of all you start with fail-passive system. Then you loose half the electricity and cockpit displays. Also, proper OEI procedure is for reduced flaps that invalidate pitch and cockpit visual reference required for LVO landings. If it is an ATR, similar problems would arise, I am afraid. 800 ft in dense IMC is not a place to sort those.

None
12th Jun 2008, 03:57
You are obligated to follow your company's published SOPs and your jet's Airplane Operating Manual. If those are not specific for your scenario, then you have an opportunity to decide what's best for your situation.

You say the scenario is a CAT II app below 1000 AFE with an engine flameout/failure with the standard annunciations. You say you are fully configured, have all the checklists done, and are trimmed.

For the aircraft that I fly, at this point I will also have all the checklists done and be stabilized on the approach. I will choose to continue the approach and land if I am able. The following may not apply to your aircraft, but it is a line out of my Flight Crew Training Manual specifically for the aircraft I fly:

"If an engine failure should occur on final approach with the flaps in the landing position, adequate thrust is available to maintain the approach profile using landing flaps, if desired. A landing using [normal flap setting] might be preferable in some circumstances, especially if the failure occurs on short final or landing on runways where stopping distance is critical. If the approach is continued at [normal flap setting], advance the thrust to maintain the appropriate speed. If a go-around is required, follow the normal missed approach/go-around procedures, retracting the flaps to [normal go-around with all engines flap setting]. Adequate performance is available.

Having said all of that, it continues with, "It is usually preferable to continue the approach using [engine-out flap setting]. This provides a better thrust margin, less thrust assymetry and improved go-around capability."

I will not make any changes to configuration this far along on a CAT II app. I will do the same thing that 411A says. Continue and land if at all possible.

This is just my take on this discussion. I realize there will be other points of view as well.

Nice flaps
13th Jun 2008, 10:15
I think something also pretty relevant in all of this is the very real possibility of going around from a Cat II app, from a 100ft decision point. As we all know, there is a strong chance of touching down during the course of this maneouvre, and that is even on the basis of having all engines operating. So I have to say that to initiate a missed app from 100ft on one engine in 300m vis is not a scenario that fills me with joy.

My SOP's dictate that above 1000ft agl we complete the memory actions before initiating a missed app, whereas below that point we go-around and then complete the memory actions after. But for us it will always result in a go-around on a Cat II app. This policy makes a lot of sense to me, but of course it does depend on a/c types and their levels of redundancy etc.