OK - So what just happened?...

[jb2_86_uk]

There I was in my B757-200 gracefully climbing to a crusing altitude of 33,000ft when all of a sudden my airspeed dropped like a stone inevitably causing the nose to pull right up stalling the aircraft. So i put the plane into a moderate dive to get a bit of airspeed back. That has never happened before. When i recovered it, i noticed that the EPR dials on the EICAS display were very low indeed - low even for the engines idling - never mind at full power which they were! I put the plane into a straight and level attitude - climbing was impossible. The aircraft (despite being at full power) would not accelerate from about 180knots (mach .45 if I remember rightly) Realising that I wasnt going to make my destination I disabled autopilot and began a 180 degree turn whilst decending at -800ft/min - Then the engines sprung back into life (not that they had died, they just seemed to have about as much power as a turtle pulling a car) and all was well and fine. Does anyone have a clue what happened?

John

PS: All other EICAS instruments and gauges were showing normal readings for the engines at full power.

[igorski]

try it again, see if it happens again  :P, you probabley just went too high for the engines, had a flame out (pls dont ask me to tell you what that actually means, but you engines go off) then when you decended they gained power again in the denser air. I assume in a real a/c that would actually occur gradually, rather than suddenly, but i may be wrong.

[jb2_86_uk]

Yeah I thought it could have been that, but they 'died' at 31000ft, came back at 30,000 then when I was back en route i climbed tomy desired 33000ft with no problem!!!! was very wierd

John

[igorski]

hmm ok, must just have been FS being a bit odd, always watch your rate of climb though, those big beasties dont like to zoom up like a lightning  ;)

[Mobius]

Do you have crashes on but don't have "allow collisions with other aircraft" checked?  If so, you probably just ran into another airplane somehow.  When you run into another airplane under these conditions, you immediately stop and your engines go to idle.  Otherwise, FS is just going nuts (or you are ).

[wji]

Maybe pitot heat was off (SHFT+H) or the plane was picking up ice on the airframe. At FL330 at a standard laps rate of -2C. per thousand feet the OAT (TAT) (Outside Air Temperature) could be -70C. Any moisture in the air will cause big problems

[Nexus]

Bill, TAT and OAT is not the same, maybe you mixed that up with SAT/OAT  :)

And I do wonder where the ice comes from at -70C since ice buildup is practically non-existant below -30C
Me thinks it's an FS9 mess up.

[Hai Perso Coyone?]

Yes, that has happend to me as well. In my case it was a 727. Same problem like urs except mine dropped at 24,000ft.

Cheers,
Ashar

PS: mine didnt recover until it reached 53 ft above the ground

[Reap]

Okay first of all which model of 752 do you have? If its a Posky model then they are overweight by default with full fuel. Also on some of them the centre of gravity is right on the nose, and I found it imposible to climb to Flight level without the same problems you had.

The answer lay in editing the aircraft.cfg to allow for manual imput on payloads which sorted the problem.

If you cant sort it i can give you the line to edit or send you a replacement cfg if you wish.

[dyfly]

Yep sounds like you got into a compessor stall it happens in jet engines. Going to high and hear pop bang and then comes the engines spooling down to nothing. So nose down get air going into chamber then a re-light on your way again It happens so watch out for service ceiling

[beefhole]

While things like a "compressor stall" may happen in real life, chances are more than likely they're not modeled in fs.

Were you flying with real-world weather on?  You may have been hit by a sudden, very strong tailwind, causing your IAS to display as much less (remember, ram air pressure).  This would explain the sudden loss of airspeed-it's happened to me before.  When this happens, just disengage the A/T and hand climb her.

EDIT: Also, I don't have it on me, but the 752s service ceiling is far above 330.

[Saratoga]

beef, even in the most extreme situation, you couldn't hit a tailwind that would send the 757's airspeed indication to zero. Unless of course you were climbing at like 120 knots or so, in which case you need to get back to flying Cessnas. If you were at the correct 280 knot climb speed, you wouldn't have gone below 180 knots, still a perfectly capable climb speed for the '57.

As for the pitot heat being a suggestion, wouldn't affect the engines. The EPR dropped because your speed dropped, i.e. no air for the engines. In reality, you would have a complete flameout on your hands if your airspeed hit zero (though that wouldn't be your biggest problem) because you wouldn't have any air going through the engines except what they suck in, which isn't enough that high.

Probably just one of those little ghosts in FS, see if you can make it happen again.

[beefhole]

beef, even in the most extreme situation, you couldn't hit a tailwind that would send the 757's airspeed indication to zero.

It dropped to zero? Oops.  Time to start reading threads before I post (a revolutionary idea)  ::)

This has happened to me twice, both times I was on approach. I'm pretty sure Pitot heat cleaned it up nicely.  And when it does happen, just throw the A/T off and control the throttle manually.

[jb2_86_uk]

Beef, your right, it didnt hit zero, it just dropped to about 180knots I think, and bearing in mind I would have been nudging 300knots or more as I had just about reached my cruising altitude. I Think it must have just been a software glitch it has never happened before and it hasnt happened since and ive not done anything different. Strange1

John

[beefhole]

You know what, i knew that too.  I was going to say something but I just assumed Saratoga was right  ::)