Simviation Forums

Hi there

Im having a problem that i never experience before  :-/..

Evertime i use the 747-200 and when i get to 30000 ft i start to lose speed,the speed starts to drop dramatic and thats it the plane stalls and nose dive,can someone give a tip of what's going on with this because i have no idea.

I can think of two things....

1. You are climbing too fast for your aircraft's weight. Climb slower to allow it to burn off more fuel before reaching your cruising altitude.

2. Your pitot tube(s) is/are iced over, and due to the erroneous readings from it, your autopilot tries to compensate and makes things worse. Pitot heat is your friend here.

I'll choose option #2. Sounds a lot like ice to me.

My question is, do you understand the relationship of indicated airspeed?  30000 feet is about the point where you start to see major reductions in indicated vs true airspeed, and have to really manage your speed (usually in Mach number, not airspeed).

[quote]My question is, do you understand the relationship of indicated airspeed?

[quote]My question is, do you understand the relationship of indicated airspeed?

Sounds more like the airplane is too heavy for the altitude. Cruise at a lower altitude for a while, then try a higher altitude. You may have to do this at a couple of altitudes until you can operate at your highest cruising altitude. This is the way it works in the real world.

If you could find an operating manual for the airplane, you'll be able to find the applicable charts.

Arts

Sounds more like the airplane is too heavy for the altitude. Cruise at a lower altitude for a while, then try a higher altitude. You may have to do this at a couple of altitudes until you can operate at your highest cruising altitude. This is the way it works in the real world.

If you could find an operating manual for the airplane, you'll be able to find the applicable charts.

Arts

Well thats exacly what i did and 50 min later i made up to 37000 feet.
Like i said before i never experience this problem before with any other plane,not even with the pmdg 747-400.

Just make sure you're not overweight at take-off; checking on the fuel/payload options should tell you whether you are or not. Then you need to 'step' your ascent, depending on plane - 767s are notorious for it.

Yep climbing too much too young too fast....    I do it all the time and end up staying at 20k for an hour...

Sounds more like the airplane is too heavy for the altitude. Cruise at a lower altitude for a while, then try a higher altitude. You may have to do this at a couple of altitudes until you can operate at your highest cruising altitude. This is the way it works in the real world.

If you could find an operating manual for the airplane, you'll be able to find the applicable charts.

Arts

Well thats exacly what i did and 50 min later i made up to 37000 feet.
Like i said before i never experience this problem before with any other plane,not even with the pmdg 747-400.

Unless your doing a couple hour flight with low fuel, 37000 feet is pretty high on a 742.  Yeah, most commercial airliners plan their weight (mostly their fuel weight) to that which is just a little over required.  I used to work for an airline, and having shadowed some load planners before, in most cases, they don't even fuel up the birds more than 10k lbs more than the required fuel load on a 737NG.  On wide-bodies and long hauls, you'd want a bit more obviously. 

So unless your doing a 12 hour flight, chop down on the fuel load a little.  Ideally you'd want a chart for this, but for a 747, I'd say usually 40k more than your required burn is enough for most purposes. 

[quote][quote]My question is, do you understand the relationship of indicated airspeed?

[quote][quote][quote]My question is, do you understand the relationship of indicated airspeed?

When 747-200 were common I often heared the pilots ask for a higher lever say from 270 to 290 and the controller say he could have 310 but the reply was negative I'm too heavy at this time.

I remember at the time the 767 went into service it was said it was the first commercial jet airliner that could take off at max load and climb to service ceiling without having to nurse it up to the higher levels as weight came off............how true that is I can't say but it shows that earlier types were not able to do this.

Another type of clearence I would here is being to told clim to a higher level at a given time which could be 30,40, 50 minuetes ahead.

In this case I would go for overload but you can checj this.

Do as you have been doing and when you get the problem, paused the sim, reduce the load and see what happens.

When 747-200 were common I often heared the pilots ask for a higher lever say from 270 to 290 and the controller say he could have 310 but the reply was negative I'm too heavy at this time.

I remember at the time the 767 went into service it was said it was the first commercial jet airliner that could take off at max load and climb to service ceiling without having to nurse it up to the higher levels as weight came off............how true that is I can't say but it shows that earlier types were not able to do this.

Another type of clearence I would here is being to told clim to a higher level at a given time which could be 30,40, 50 minuetes ahead.

In this case I would go for overload but you can checj this.

Do as you have been doing and when you get the problem, paused the sim, reduce the load and see what happens.

As airline aircraft have developed, the have more power to climb to the higher altitudes.  20 years ago, you would rarely see an airliner above FL350, while today it is common to find many all the way up to FL410.