irrational fear of flying

[rwsaunders]

I sent a pic of this exposed cable on our 757-200(OW) to Mrs. RW last evening before we departed so that she had some evidence for the personal injury attorneys. Somehow we missed all of the mountains and water and made a safe landing. I did tell the FA about it when we were leaving and he said that it had already been reported. When I told him that I tugged at it a bit and that when it sparked I stopped, he paused but then got the joke.

[SteveP]

something I had never heard of...
50 American Airlines flights out of Phoenix were cancelled the other day.
The planes cannot lift off if the temperature is over 122f.
Not enough lift.

if I remember, this was one model of aircraft.
maybe a pilot could chip in.

[rwsaunders]

I’m not a pilot and I don’t play one on TV, but this is common with the regional l jets, like the ERJ’s and CRJ’s. I have had flights cancelled for this reason and they were all out of Sky Harbor in Phoenix. Makes you feel good doesn’t it?

The Science Of Why It's Too Hot For Some Planes To Fly In The Southwest U.S.

[Saab2000]

The absolute temp reading itself is not the issue as much as the deviation from the ISA standard temp for a specific elevation. PHX is 1135’ or so above sea level so the ISA Standard temp is (rounded) 13°C. 122°F is 50°C. The limit for takeoff for a previous type I operated was ISA+35°C. In the example given, the deviation from standard is 32°C, which exceeds this limit.

I’m not sure if that limiting factor is climb performance (lift, at least that is part of it) or engine performance. Depends on the specific type. My guess on my old type is engine certification limits. The manufacturer sets limits which are approved by the certifying agency, (in the US all airplanes have to meet FAA standards) and this becomes an operating limitation.

Would it fly? Yes. Is it safe in case of an engine failure? Maybe not based on terrain limits or other factors.

I’m no engineer or test pilot, so it’s likely there is a better or more thorough explanation. But hopefully this sheds some light.

ISA is the International Standard Atmosphere and is 15°C for the purpose of this discussion.

[Saab2000]

I’m not a pilot and I don’t play one on TV, but this is common with the regional l jets, like the ERJ’s and CRJ’s. I have had flights cancelled for this reason and they were all out of Sky Harbor in Phoenix. Makes you feel good doesn’t it?

The Science Of Why It's Too Hot For Some Planes To Fly In The Southwest U.S.

Actually, we should feel good about it. It means the engineers figured safe limits instead of just putting our fingers into the wind and saying, “I think she’ll fly”. That is no longer good enough because it’s not the 1930s any more.

I have almost 10,000 hours flying CRJs and during the time I was at the company that flew this type I estimate we flew nearly 2.2 million individual flights at that company alone, every one with a safe outcome. That does not happen by random chance. It happens by good engineering, training and flight crew discipline. And operating within the limitations and sometimes that means canceling flights.

[rwsaunders]

Actually, we should feel good about it. It means the engineers figured safe limits instead of just putting our fingers into the wind and saying, “I think she’ll fly”. That is no longer good enough because it’s not the 1930s any more.

I have almost 10,000 hours flying CRJs and during the time I was at the company that flew this type I estimate we flew nearly 2.2 million individual flights at that company alone, every one with a safe outcome. That does not happen by random chance. It happens by good engineering, training and flight crew discipline. And operating within the limitations and sometimes that means canceling flights.

Saab...I made the statement that it makes me feel good that they've identified the limits and not from a negative perspective for sure. I always moan about flying but it's not the actual flight that I moan about. In fact, my wife always comments that I act like a kid on his first flight every time that I fly! Window seat for me, ma'am. It's the bureaucracy of the process and lately, people with their bare feet, muzzled dogs and nasty smelling fried whatever sandwiches on the 5:30 am flights that make me wonder why I do it.

[Saab2000]

The limit for takeoff for a previous type I operated was ISA+35°C. In the example given, the deviation from standard is 32°C, which exceeds this limit.

I mistyped. It was ISA+ 30, IIRC. In a hurry in an airport typing on my telephone. Anyway, there are limits and we have to respect them. To this point, a crew at my old carrier was stranded for several days because the lower limit for this particular type was -40ºC and for a few days in the early 2000s in Edmonton it didn't rise above -40ºC and this was a "Show Stopper". I flew the same airplane in and out of Montreal many times and a few times it was in the low -20ºC range, close to -30ºC and the engine was near the starter time limitation to get it to light off. There are many reasons for these limits and not all are obvious. Kerosene is a bit slower to burn at these temps and the limit of the starter motor may be the limiting factor.

[jclay]

Actually, we should feel good about it. It means the engineers figured safe limits instead of just putting our fingers into the wind and saying, “I think she’ll fly”. That is no longer good enough because it’s not the 1930s any more.

I have almost 10,000 hours flying CRJs and during the time I was at the company that flew this type I estimate we flew nearly 2.2 million individual flights at that company alone, every one with a safe outcome. That does not happen by random chance. It happens by good engineering, training and flight crew discipline. And operating within the limitations and sometimes that means canceling flights.

^^Doesn't merely hit the nail on the head; drives it through the board and into the next county. I'd only note the inadvertent omission of serious, first world regulations of the aircraft, aviation and supporting industries.

[jclay]

The Science Of Why It's Too Hot For Some Planes To Fly In The Southwest U.S.

WRT the Forbes article, and its note that some of the larger aircraft were within their take-off performance envelope at high air temps: Since the CRJ has a wing loading at the low end of the spectrum for commercial passenger aircraft (around 102#/sf in a spectrum ranging from ~100 to ~140, based on a small sample of interweb info) it's take-off limitations related to air density (temp) are likely based much more on raw engine performance or a low thrust to weight ratio, than lifting performance (where it should have a comparative advantage to, say a 737 @140#/sf).

A quick check of max take-off thrust to max take-off weight gives a thrust to weight ratio of 0.17 for the CRJ. A 737 is about 0.31 and an A380 is 0.23, larger representing more thrust for a given weight. Again, this is all based on raw data that I just got off of the interweb.

I'm not a propulsion engineer but based on first principles my guess is that larger diameter fans found on larger aircraft (under hung engines with lotsa room for large diameter turbines) are more effective at producing thrust at a given engine pressure ratio (performance of which is air density dependent) than engines with smaller diameter turbines (a typical limitation of fuselage mounting). I'd also expect the thrust differences to be related to the square of the turbine radius (the area of the turbine “plate”).

In spite of the CRJ's advantage in lower wing loading (which surprises me, just looking at it...I'd have guessed higher loading) it looks like the big engines can simply muscle the larger aircraft down the runway more effectively generally, and suffer less low density performance degradation, than the smaller diameter engines of the CRJ types.

That's my story, and I'm sticking to it.

As an aside: I'm continuously amazed at the performance and reliability of modern turbine engines. I have a reasonable handle on what's going on in there, and in the airplane in general, and there's not a flight I'm on that it doesn't blow my mind. Just the effing bearings for the turbine shaft.....what it takes, the technology, science and manufacturing to make just the bearings is enough to explode my mind.

[SteveP]

so, the planes in question can land but are not allowed to take off again.
seems like a pretty big problem for a busy airport in a busy an extremely hot part of the country.
I wonder how many days a year this happens.

[jclay]

so, the planes in question can land but are not allowed to take off again.
seems like a pretty big problem for a busy airport in a busy an extremely hot part of the country.
I wonder how many days a year this happens.

I'd imagine it's just an economic decision (choice of aircraft against the cost of this sort of problem). Of course if the frequency increases then the calculation will yield different results!

[rwsaunders]

so, the planes in question can land but are not allowed to take off again.
seems like a pretty big problem for a busy airport in a busy an extremely hot part of the country.
I wonder how many days a year this happens.

Forget hot weather...the strikes in CDG have a major impact in terms of flight delays in Europe.

French air traffic control 'causes third of Europe's air traffic delays' | World news | The Guardian

[SteveP]

Forget hot weather...the strikes in CDG have a major impact in terms of flight delays in Europe.

French air traffic control 'causes third of Europe's air traffic delays' | World news | The Guardian

funny this is here the same day that I booked a flight in CDG for later this year.
wish me luck.

[rwsaunders]

While I'm chilling with Mrs. RW last evening I can hear a turboprop circling above the house every 10 minutes or so. After about 30 minutes, curiosity got the best of me and I fired up my trusty Flightradar24 app. I note that there were actually two planes circling at approximately 8,500' and this went on for over 2.5 hours. One of the planes was identified as IRONS12 which I couldn't find on the web and the other was registered as 05-0429. A little digging on Online spotters logbook and aircraft registration database - PlaneLogger noted that was a Pilatus PC-12 which was registered to the US Special Forces-HQ AFSOC in 2005 and is active. They eventually landed at a small airport SW of the city and that was it. If I see or hear black helicopters tonight, I'm headed to Idaho.

Registration Details For 5-429 (US Special Forces-HQ AFSOC) Pilatus PC-12- - PlaneLogger

[rwsaunders]

They’re back again this evening...should I be nervous?

[Mabouya]

They’re back again this evening...should I be nervous?

Check the street outside - is this van parked a few houses down from yours?

If so, I think they've finally found you, and you'd best use your secret tunnel to the sewers to escape asap.

[Scott G.]

The SOCOM PC-12s have special Toyota Hi-Lux and Land Cruiser sensors,
the standard vehicles for bad guys the world over.
Check your area.

[rwsaunders]

Although I'm posting this along with Jason Bourne from a CIA safe house somewhere in Eastern Europe, I now know the reason for the air activity. At least this is what we are telling the public...

Why are there helicopters circling over Pittsburgh? | WPXI

[mnoble485]

RW,
They have read the “What are you cooking for dinner” thread and are waiting for an invite.

Miek

[busdriver1959]

something I had never heard of...
50 American Airlines flights out of Phoenix were cancelled the other day.
The planes cannot lift off if the temperature is over 122f.
Not enough lift.

if I remember, this was one model of aircraft.
maybe a pilot could chip in.

It’s possible the limiting factor is the takeoff data source. Back in the 1990’s, Phoenix had a heat wave. Our takeoff data wasn’t run on a computer, it came out if thick books of tabulated data. The highest temperature in the tables was 120F. You couldn’t legally takeoff until the temperature cooled back down below that temp, period. The airplane would fly, you just needed more airspeed to do it and therefore more runway but you didn’t know how much because you didn’t have the data.
We now run our takeoff data on computers and I don’t know the upper temp limit. I’m pretty sure the data has to come from flight testing and I doubt there is any modeling that the FAA would allow to generate data outside the actual testing conditions. I could be wrong though.
It’s up to the aircraft manufacturer to generate all of this data. At some point they have to draw the line on the environmental conditions they’ll generate data for. That becomes the legal limit.