Hey, jet pilot types, learn me something'

Vector4Food

Vector4Food

This job would be easier without all the airplanes
Had a pilot call in a panic tonight..

"we need a descent, the deviation is +16"

Gave it to him, but what exactly does that mean?

Made me feel like a woman being told her headlight fluid is low..."is that a thing? Better not ask and look stupid"
 
That's my guess too. They probably didn't have performance numbers for a temperature that high, or were above the altitude they could be at for their performance numbers.
 
canadian_atc said:
Had a pilot call in a panic tonight..

"we need a descent, the deviation is +16"

Gave it to him, but what exactly does that mean?

Made me feel like a woman being told her headlight fluid is low..."is that a thing? Better not ask and look stupid"
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If ISA + 15 is a limitation on their aircraft, then they're violating a limitation of the aircraft by staying at that altitude, and would likely be treated as no different as over speeding the aircraft.
 
More likely they were able to crawl up to altitude, but once they got there speed decreasing they realized that they couldn't "stay" up there. With speed decreasing they might have had to come down in a hurry. (Not that I've ever seen something like that happen before...)
 
ZapBrannigan said:
More likely they were able to crawl up to altitude, but once they got there speed decreasing they realized that they couldn't "stay" up there. With speed decreasing they might have had to come down in a hurry. (Not that I've ever seen something like that happen before...)
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Yeah but, what airplane would have that problem with a deviation of +16? My pesky little RJ is certified up to ISA + 35.
 
I fly an airplane with performance that makes an RJ look like a Cessna 150 running on 3 cylinders and climbing through the high 30s with ISA+10 or greater the old girl can run out of steam. There are temperature and altitude combinations that just don't work.

I believe your ISA +35 is probably a takeoff limitation, no?
 
jtrain609 said:
Yeah but, what airplane would have that problem with a deviation of +16? My pesky little RJ is certified up to ISA + 35.
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That isa+35 is meant for ground ops performance. Isa +15 could be pretty serious for most underperforming jets like your little rj and light jets at their max altitude. Granted they should know as a crew what the temperature is going to be before they get there and what the performance is going to be like.
 
I've yet to use a flight planning service that didn't include info about ISA deviation on the entire route.

I think this is kinda like crew I hear that obviously haven't looked at an enroute.
"Airline 456, cleared direct CARPX"
"Uhh, is that Charlie Lima Bravo?"
"No, that's Charlie Alpha Romeo Papa Xray. CARPX, on your route of flight."
 
ZapBrannigan said:
I fly an airplane with performance that makes an RJ look like a Cessna 150 running on 3 cylinders and climbing through the high 30s with ISA+10 or greater the old girl can run out of steam. There are temperature and altitude combinations that just don't work.

I believe your ISA +35 is probably a takeoff limitation, no?
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All operations are limited to ISA + 35, takeoff is limited to +52 C.

Additionally, they scaled this thing back. The real ceiling in the aircraft is FL410, but it was limited to FL370 with the RJ model. Some folks say to provide some buffer for low time pilots so they couldn't get themselves back into a corner at higher altitudes, some say it was done in order to increase the life of the airframe. In any event, this thing would have no problems climbing another 4,000', and at that point, you may find problems with performance, but this may be why I've never seen the plane take a crap with high ISA temps. Slower climb? Sure, but I've never thought to myself, "ZOMG, this thing won't make it!" We can make it directly to the service ceiling at nearly any weight.

Also, we climb slow as it is. The XR's climb at 290 to .60, and I've never had a problem holding that through FL370 on most days. And even on hot days when the climb rate starts to decrease, I've never seen the thing fail to accelerate once you level off.
 
TFaudree_ERAU said:
I've yet to use a flight planning service that didn't include info about ISA deviation on the entire route.

I think this is kinda like crew I hear that obviously haven't looked at an enroute.
"Airline 456, cleared direct CARPX"
"Uhh, is that Charlie Lima Bravo?"
"No, that's Charlie Alpha Romeo Papa Xray. CARPX, on your route of flight."
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You're a stud

Normally for me it goes down something like this

"RJ xxxx cleared direct CARPX"
"Clearrrrrrrrred....diiiiirrreccccccttttt....(quickly flipping through the legs page to find something that closely matches what he just said)....CAAAAAAAAR(found it)PX!"
 
Jimmy_Norton said:
Did you manage to do it without stalling? Miracles never cease....

They got killed cause they were stupid, plain and simple.
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No, they got killed because they weren't properly trained. No one gets into an airplane and says "I think I'm going to do something stupid today and risk my life." They didn't have the required knowledge to know that what they were doing was something stupid and dangerous. Frankly, very few pilots at Pinnacle at the time did. The captains were all Saab drivers who were thrown into a jet with a super-critical wing without anything resembling high altitude performance training, and most of the FOs had under 1,000 hours and were still trying to figure out visual approaches, let alone high altitude stalls.

And if memory serves, the temperature that night at FL410 was ISA+13. So yes, in the right airplane, getting up close to limit altitude at ISA+16 is a serious thing, and you would definitely want to come down pretty quick. Forecasts aren't always accurate, either. A forecast of ISA+10 may be just fine, but if you find out after climbing up that it's ISA+15, your plan has to change. My current airplane is overpowered for its limit altitude, but I never pick up something to read until after we've reached cruising altitude and I can see that it's stable. Temps can be higher than forecast, payload weight could be higher than the rampers reported, etc. Several airlines have had high altitude stalls because the crews weren't paying attention to what was going on with their airplanes. I refuse to be the next one.
 
TFaudree_ERAU said:
I've yet to use a flight planning service that didn't include info about ISA deviation on the entire route.
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This is quite true, but I have been surprised before. I was over the North Sea two months ago and ISA spiked for about an hour to +11. Forecast TD was +3. We had planned at FL430 in lieu of FL450 to mitigate the possibility of not being able to maintain .82M if such a thing occurred. Glad we did!

Call me a wuss, but I'll generally plan oceanic crossings roughly 4,000 feet below optimum to prevent surprises. If they are able to let me climb at 30W, I'll do it.
 
Jimmy_Norton said:
Did you manage to do it without stalling? Miracles never cease....

They got killed cause they were stupid, plain and simple.
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I'll let ATN's reply do most of the talking, since I wasn't even there for that but:

There is a good reason the entire industry is limited to FL370 in the CRJ-200 now... It should have never been certified to 410 in the first place, considering that the legs you can get it up there on aren't even remotely comfortable time-wise for passengers.
 
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