Airlines canceling flights because the air is too hot

[dixiegrrrrl]

Link to tweet

darn, the tweet did not show up..

It is from author James Fallows who reported his canceled flight, saying
"First-leg flight ystrdy couldn’t take off at 3pm because *the air was too hot.*
Beyond airline’s operating specs. “Happening more often,” pilot says."

[Achilleaze]

1. republican lies about climate change are dangerous

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republican lies about climate change are dangerous
republican lies about climate change are dangerous
republican lies about climate change are dangerous
republican lies about climate change are dangerous
republican lies about climate change are dangerous
republican lies about climate change are dangerous
republican lies about climate change are dangerous
republican lies about climate change are dangerous
republican lies about climate change are dangerous
republican lies about climate change are dangerous
republican lies about climate change are dangerous
republican lies about climate change are dangerous
republican lies about climate change are dangerous

[JCMach1]

2. I call BS... Why is Emirates regularly able to operate

In 120 heat then?

[Moostache]

4. Maybe the planes are designed for more lift to operate there?

I do not know...just spit ballin'...but if you operate planes routinely in extreme conditions, you probably have specialized them to adjust to the conditions...I am assuming the airlines operating domestically are not prepared to that degree? (bad pun seen after typing...)

[underpants]

8. Good guess on lift. Depends on type of plane and length of runway

Some answers here

https://www.google.com/amp/s/www.telegraph.co.uk/travel/travel-truths/why-planes-too-hot-to-fly-heat-aircraft/amp/

[The Velveteen Ocelot]

52. Long runways.

Planes can usually take off and land in high temperatures if the runway is long enough (though there are other issues, like brake overheating). The issue is density altitude - high temperatures have the same effect on the ability of an airplane to take off as high altitudes; in both cases the air is less dense so the engines are less effective and the less dense air flowing over the wings creates less lift. The longest runway at (hot) King Kahlid airport at Riyadh is almost 14,000 feet long, while the longest runway at (cold) KEF (Reykjavik, Iceland) is only 10,000' long - but both airports handle large, wide-body and military aircraft. El Alto in Bolivia, at a field elevation of over 13,000' msl, has a runway almost as long as King Khalid's, but because of the altitude, not the heat.

[shanti]

5. Or here in Sacramento

It regularly goes above 100 here, and they don't stop flights.

[underpants]

9. Good question. I'm gathering that it depends on the plane and length of runway

I did a quick search - below.

This article doesn't address you question specifically but it has some good info

https://www.google.com/amp/s/www.telegraph.co.uk/travel/travel-truths/why-planes-too-hot-to-fly-heat-aircraft/amp/

[VMA131Marine]

14. Emirates operates out of Dubai

which is essentially at sea level. Salt Lake City is at 4,226 feet above sea level so on a standard day, the aircraft's take-off performance is as it would be at an altitude of 4,226 feet. As the temperature gets hotter and at high humidity, the density altitude increases causing take-off rolls to become longer because the wings need to move faster through the air to produce enough lift to fly and engine thrust decreases, which reduces acceleration.

A take-off is legal as long as there is enough runway remaining for the aircraft to stop up to a speed called V1 (see below). My conclusion is that for some aircraft at SLC yesterday, the among of runway that would have been used getting up to V1 because of the high density altitude, would have resulted in too little runway remaining to stop in the event of an engine failure at V1.

V1 is the critical engine failure recognition speed or takeoff decision speed. It is the speed above which the takeoff will continue even if an engine fails or another problem occurs, such as a blown tire.[9] The speed will vary among aircraft types and varies according to factors such as aircraft weight, runway length, wing flap setting, engine thrust used and runway surface contamination, thus it must be determined by the pilot before takeoff. Aborting a takeoff after V1 is strongly discouraged because the aircraft will by definition not be able to stop before the end of the runway, thus suffering a "runway overrun".[34]

V1 is defined differently in different jurisdictions:

The US Federal Aviation Administration defines it as: "the maximum speed in the takeoff at which the pilot must take the first action (e.g., apply brakes, reduce thrust, deploy speed brakes) to stop the airplane within the accelerate-stop distance. V1 also means the minimum speed in the takeoff, following a failure of the critical engine at VEF, at which the pilot can continue the takeoff and achieve the required height above the takeoff surface within the takeoff distance."[7]
Transport Canada defines it as: "Critical engine failure recognition speed" and adds: "This definition is not restrictive. An operator may adopt any other definition outlined in the aircraft flight manual (AFM) of TC type-approved aircraft as long as such definition does not compromise operational safety of the aircraft."[8] - Wikipedia


The density altitude is the altitude relative to standard atmospheric conditions at which the air density would be equal to the indicated air density at the place of observation. In other words, the density altitude is the air density given as a height above mean sea level. The density altitude can also be considered to be the pressure altitude adjusted for a non-standard temperature.

Both an increase in the temperature and a decrease in the atmospheric pressure, and, to a much lesser degree, an increase in the humidity, will cause an increase in the density altitude. In hot and humid conditions, the density altitude at a particular location may be significantly higher than the true altitude.

In aviation, the density altitude is used to assess an aircraft’s aerodynamic performance under certain weather conditions. The lift generated by the aircraft’s airfoils, and the relation between its indicated airspeed (IAS) and its true airspeed (TAS), are also subject to air-density changes. Furthermore, the power delivered by the aircraft’s engine is affected by the density and composition of the atmosphere. - Wikipedia

[A HERETIC I AM]

15. Dubai's long runway is 14,000 feet.

Over 2.6 miles.

https://goo.gl/maps/xgjTDq1rtzn
Just to add info

[VMA131Marine]

19. That helps too!

It's designed with high density altitude in mind. SLC's is only 12,002 feet.

[A HERETIC I AM]

23. Yup

It's interesting when you research the alternate runways they had reserved for Shuttle launch aborts. Same sort of criteria. Long enough to deal with summer heat, etc.

[uponit7771]

39. Dubai is at sea level any higher in the temperature go higher there's less air density

[denbot]

41. Altitude

Higher the altitude, the thinner the air to begin with, heat will exasperate the air density, and inhibit lift.

[fescuerescue]

42. The planes are capable

But everything is pre-calculated for the air temp, runway, aircraft, weight, fuel, etc etc for various things like take off speed, point of no return etc etc etc.

If those tables arent pre-populated with the larger numbers, you aren't allowed to just "wing it". That happened in Phoenix a few years ago during some record temps. Sure you've got a table for 119 degrees, but if you don't have one for 120 degrees and 120 degrees. You aren't moving (legally)

In areas where the temp is routinely hotter, those tables are already calculated.

[Major Nikon]

50. Because temperature is one variable out of many

Aircraft type, certification specs, passenger and fuel loads, altitude, barometric pressure, wind speeds, runway length, runway slope, overrun distances, wind speed, required climb gradient, and probably a few other variables I’m missing off the top of my head.

Most airlines are going to operate their fleet near the limit of their certified capabilities at least for some of their routes. If the temp is higher than expected during the hottest part of the day, they have few options besides cancellations.

[Timewas]

77. It is called

Density altitude, 120 degrees at sea level aircraft may be able to take off ok, same temp at 5000 feet not so much, 90 or so at south lake tahoe airport you might end up in the lake..

[JI7]

3. how does hot weather affect it ?

[underpants]

6. I looked it up - air density

Why can't planes fly in the heat?

Hot air is less dense than cold air, meaning aircraft require more engine power to generate the same thrust and lift as they would in cooler climes. The conclusions are in part logistical and in part safety, as author and pilot Patrick Smith explains in his book, Cockpit Confidential.

“Hot air is less dense than cold, negatively affecting both lift and engine performance,” he writes. “The take-off roll will be longer and the climb shallower, and in very hot temperatures, a plane may no longer meet the safety margins for a particular runway - climb gradient parameters and the weight is determined for every take-off based on weather and runway length.

https://www.google.com/amp/s/www.telegraph.co.uk/travel/travel-truths/why-planes-too-hot-to-fly-heat-aircraft/amp/

[Stinky The Clown]

7. Heat and airport altitude affect the air which in turn impedes the wing's ability to lift.

Simple physics.

DEN, for example, has a bigger problem than SFO.

[Major Nikon]

51. It also affects the engines ability to make power

When air molecules get farther apart, there’s less of them available for combustion.

[lapfog_1]

11. air density

hot air is less dense than cold air.

Air provides lift.

As air moves over the wings of the craft, the curve the wing causes the air moving over the top to move faster than the air on the bottom... that difference creates lift and the airplane flies as a result.

However, the shear number of air molecules in the volume of air directly in the path of the wing plays into the equation as well.

This makes a big difference when the plane is moving relatively slowly (like takeoff and landing) and also has to do with the surface area and curvature of the wing (flaps are extended for takeoff and landing).

However, air temperature is critical too... hotter air, less air density, less air pressure on the underside of the wing even with flaps fully extended... less safety margin.

My guess is that for airlines that fly into airports where hot surface temps are common is that they choose a fleet of planes that meet certain specifications... or maybe they simply ignore some safety margins.

(old NASA aerodynamics person, specifically computational fluid dynamics - our motto was "rocket science is easy... aerodynamics is hard&quot

[oberliner]

10. Nope, turns out it was technically never too hot to fly out of Phoenix

It turns out it was never really too hot to fly out of Phoenix.

The airlines just needed bigger numbers.

Last summer, American Airlines canceled 60 regional flights over three days as temperatures neared 120 degrees. Those cancellations made national news, with stories that proclaimed Phoenix as the city where it was too hot to fly.

On Tuesday, as temperatures in Phoenix again flirted with the 120-degree mark, American Airlines issued a news release saying there was no danger to travelers of a repeat flurry of canceled flights.

What happened last year, the airline said, was math-related, not heat-related.

https://www.azcentral.com/story/news/local/phoenix-weather/2018/07/24/phoenix-flights-never-too-hot-fly-out-sky-harbor-airport-american-airlines/827871002/

[JCMach1]

20. Yep, BS company excuse...

Good catch

[mr_lebowski]

21. Doesn't prove the story in the OP is untrue ... read the rest of the posts on this thread from

many who certainly appear to know what they're talking about.

Phoenix likely has longer runways than SLC ... 120 is expected in Phoenix ...

[JCMach1]

24. Our American agencies got the math wrong

https://www.azcentral.com/story/news/local/phoenix-weather/2018/07/24/phoenix-flights-never-too-hot-fly-out-sky-harbor-airport-american-airlines/827871002/

It can get too hot, we were calculating the safety margin incorrectly, however...

[mr_lebowski]

25. The story in the OP is not about flights in Phoenix.

Ergo, past failings or even lies ... in Phoenix ... are basically a non-sequitur.

[JCMach1]

29. Well, even if we look at old FAA guidance, how many cities in CONUS

Have been higher than 117F this Summer?

Boeing and Airbus have even higher parameters...

Answer goes back to OP.


Now, have there been cancellations because cabins are too hot? That's another story

I have been on one of those flights before... Couldn't breathe... 90+ cabin temperature on hot tarmac

[Major Nikon]

70. Temperature is relative to altitude

It takes more runway in Cheyenne at 70F than it does in Phoenix at 120F.

[Hassin Bin Sober]

33. They didn't get the numbers wrong. The company engineers updated their operating limits.

That doesn’t mean the airlines lied.

It means the safety margin was trimmed to fit.

Good luck everyone!

[Major Nikon]

66. Not necessarily

When a plane is initially certified it has to be tested for all the conditions it’s expected to operate within. Manufacturers aren’t going to test for every conceivable scenario. Sometimes what happens is an operator finds themselves wanting to operate outside of those conditions so they have to go back to the manufacturer for numbers for those conditions. It’s actually quite common.

That doesn’t mean safety margins are trimmed. It may mean they can’t operate with the same fuel and cargo.

[oberliner]

26. Not meant to - just thought it was interesting info

Related to the topic brought up in the OP.

[Hassin Bin Sober]

34. Yes. It was, in fact, technically too hot to fly - based on the manufacturers charts.

That’s the law. The airlines have to abide by the charts the manufacturer provide (and FAA signs off on).

That headline makes it sound like the airlines were gaming the system. They weren’t. If anything, the safety margin was trimmed a little bit.

Safety margins are generally a bit conservative. Generally. Let’s just hope trimming the margins for company profit doesn’t go too far.

Pushing the envelope bites us in the ass every once in a while. Let’s hope this adjustment doesn’t someday wind up being a link in a chain that leads to a tragedy.

Perhaps a pilot enters a wrong fuel calculation, a plane gets loaded with unusually large passengers in our “growing” population and a plane attempts to take off on an unusually hot/humid day with a sudden wind change/gust on the tail. Good night Irene...

[oberliner]

40. Thanks for adding that

This is a really interesting topic that I am learning so much about!

[The Velveteen Ocelot]

59. Yes. A pretty considerable margin is built into the numbers.

For large airlines all the performance information is calculated by the dispatch department and sent to the crew before takeoff by ACARS (pilots don't have to do the math any more). If the numbers don't work in the first instance the flight won't be dispatched at all.

[Demovictory9]

75. interesting

[Major Nikon]

54. Technicallies are a big deal in commercial aviation

Every transport category airplane has a set of numbers used for operations you get from the aircraft manufacturer. Regardless of whether the aircraft is capable or not, operators are required to stay within those limits unless there’s an emergency. Doing otherwise puts the pilots’ and airlines’ certifications would be in jeopardy otherwise and if an accident occurred there would be liability.

[The Velveteen Ocelot]

55. The FAA takes "technicalities" very seriously.

I used to work for a large airline. There was no question about fudging any of those numbers, ever. Before takeoff the crew would get their takeoff info, including weight, fuel, runway, weather, etc. over ACARS (a sort of text message system), and if the weather changed in some way that made a takeoff on that runway at that time impossible, either a different runway would be assigned by dispatch or the flight didn't go at all. No exceptions.

[Major Nikon]

58. Part 91 and 135 get a bit looser

In theory they shouldn’t but the reality is it does, at least with some operators. As a contract pilot you learn who you don’t want to fly with.

[The Velveteen Ocelot]

61. Having a dispatch department with computers and ops specs written in stone

makes the major airlines very safe with respect to aircraft performance. You just can't play games with the performance numbers; if the math doesn't work you don't get a dispatch release and you aren't going anywhere.

[Major Nikon]

63. Less people involved in corporate aviation

Go-no go is up to the pilots in most situations. Some of the bigger 135s have a bit more oversight which I suspect is as much insurance driven as the FAA. There’s more pressure from the rich guy in the back who doesn’t want to miss his tee time.

A crew crashed a Challenger in Aspen a few years back because the boss told them if they didn’t show up they were out of a job. Aspen is tricky even in good conditions. They tried to land with 24 kts on the tail. The plane is only certified for 10.

[The Velveteen Ocelot]

65. It's better now than it used to be but there is a lot less oversight.

My airline job was in the training department. I recall we hired a new pilot who had been flying charters for years, and of course he had to do all the weight and balance and performance calculations himself. He was just amazed and delighted to learn that we had "people" for that - though we still had to teach performance stuff, like slippery/contaminated runway restrictions. But we didn't have to make them figure out the CG or MAC or that kind of thing.

[Major Nikon]

67. You have to do all of it yourself

Thankfully most of it is on the iPad, although those apps aren’t cheap. Without it sometimes you have to get out the spaghetti charts.

[The Velveteen Ocelot]

68. This was early 2000s, pre-iPad. Poor slob was probably doing it

on one of those old charts, using a pocket calculator. I know how to do it (or used to, anyhow) but I'd rather not.

[Major Nikon]

69. The jet I fly was certified back in the 90's so probably the same deal

It’s pretty simple most of the time as you just look the numbers up in the book. It only gets tricky when you are operating near limits, or when you find out at the last minute the boss wants to bring two more couples with bags after you have loaded fuel. The worst of it is managing the catering and the dozens of other details the airline guys don’t have to deal with. Flying is the easy part.

[Tipperary]

12. Sounds like bs. Flights out of south Florida every damn hour. And it is HOT here.

[VMA131Marine]

22. Florida is at sea level, basically

Runways are also built with enough length to accommodate the typical conditions.

[LanternWaste]

31. Thankfully, alternative facts are irrelevant to science.

Physics is a difficult subject to understand. And often, when we're unable (or even simply unwilling) to use physics, we often rely on the wholly unsupported "sounds like bs" to better pretend reality conform to our biases.

[fescuerescue]

43. Altitude matters to.

High Temp and High Altitiude is a problem.

Higher Temp low altitude can be quite safe.

The temp limits for mile high Denver are going to be much much lower than for sea level Florida

[The Velveteen Ocelot]

56. Not BS at all. It will depend on FAA regs, airline ops specs,

and runway length. Since FL is at sea level it's possible to take off at higher temperatures than at a higher altitude airport at the same temperature. Airlines do NOT want to cancel flights; it screws up their scheduling throughout the whole system.

[trof]

13. Retired airline pilot here.

One consideration: The hotter the OAT (Outside Air Temperature) the less dense the air is, the longer the takeoff roll to achieve flying speed. Sometimes, at heavier weights or short runways, there's not enough runway for a safe takeoff.

Also, tires have limiting temps. Takeoff, landing, and braking generate a lot of friction heat.


When I was flying fighters in southern U.S. in summer there were times when I could not take off with a full fuel load.

[A HERETIC I AM]

16. I fucking hate you.

You obviously had a shitload more fun in your 40's than I did.


I hope you have heartburn tonight.

Wanker.

[trof]

17. It was good.

[A HERETIC I AM]

27. I'll bet.

I was --->this<--- close to going in the Army as a Warrant Officer in the early 80's. I wanted to fly helicopters so bad I could taste it. I had all the aptitude as well. The recruiter said I scored in the 95th percentile on the ASVAB's for helicopter pilot candidate (or whatever it was called back then)

I've read with envy your posts relating to your time as a pilot over the years. You and the others who made their careers in aviation.


One motivational speaker I heard once suggested you ask yourself, What am I?"

It is not an easy question to answer.

I finally arrived at mine.

I am a Machine Operator. I can operate any machine. ANY machine. If I can't figure it out on my own, I won't need any more instruction than the next guy. I KNOW I can fly. I KNOW it. I have never had a lesson, but I have been at the controls of light aircraft. I just simply know that if I had made a few decisions differently earlier in life, I would be flying for Emirates or Polar or Lufthansa or someone right now.

Instead, the machine I decided to operate was a tractor trailer!

Not too many regrets, however. I've done a lot of good over the last 40 years. Seen a lot of scenery. Brought a lot of things to a lot of people. Of that, I suppose, I can be proud.

"Keep the shiny side up" is a wish both of us can aspire to!

All the best, Trof.

Paul

[trof]

28. I was lucky enough to be there during some of the golden years.

Before airline deregulation, when the Civil Aeronautics Board still ran things.

Sounds like you're good at and happy with what you do.
That's about all anyone can ask for.
All the best to you too.

[A HERETIC I AM]

30. A family friend used to fly for National.

about as many hours in a 727 as one could get.

He used to tell us stories.

Coming in to MIA from the west over the Gulf and as soon as he got clearance to begin descent, throttled back.

Basically coasted downhill from west of Fort Myers to the Piano Keys of 9 R at MIA and didn't touch the throttles till it was time to reverse.


Fuck me, that sounds like fun,.

[trof]

32. Oh yeah.

Used to do that from Chicago to Columbus, Ohio if they were landing runway 10.
As soon as we got handed off from Chicago to Cleveland Center request descent clearance "as needed".

[A HERETIC I AM]

36. "This is your Captain speaking"......

"In spite of the fact that I am charged with protecting the lives of you 140 odd fuckheads, I'm going to have a bit of fun.

Enjoy your flight"




Oh yeah.


LOL....

It is a serious .....well...yeah...tragedy...it is a tragedy, that more young people aren't interested in your profession.

It is interesting that the two professions in this country that are in serious need of new recruits are truckers and pilots.

I mean...what the fuck?

It is the barrier to entry. That's the problem. It's too expensive to learn how to become an airline pilot if you don't follow the military route and the length of time from newb to line left hand seat (ie: the big bucks) is too long. Of course, I get the fact that you can't put a C-172 driver with 100 hours in the sharp end of a B777, but there has to be a better way. Hell, I read where Emirates is parking some of their A 380's because they don't have enough qualified pilots.

Same with trucking, in that it takes several years of eating crap before you can get on with a decent company and make good money and have decent working conditions.

What does/will it take to interest the younger generation (besides the obvious:pay) to get into the professions that require extensive travel and need a brain to do it?

[trof]

48. I wouldn't advise a young person to be a commercial pilot today.

The job ain't what it used to be.
Wages, benefits, and working conditions.
Going the civilian route to get your tickets is way too costly.

Military is the way to go, but even that opportunity is dwindling.
Think "drones".

Right now my dream aviation job would be with a trash hauler.
Fedex, UPS, Nippon Cargo, etc.

No pax to deal with and pretty good pay and benefits.

[Major Nikon]

71. It's getting better

Pilot shortages are starting to take their toll.

[Major Nikon]

57. Part 91 gets interesting during high, hot, and heavy

Sometimes you see red centerline lights going under the nose before rotation.

[The Velveteen Ocelot]

62. I remember taking off from Santa Fe (6,350') in a C-182,

and finding the takeoff roll to be disconcertingly long...

[Major Nikon]

64. I was at Leadville two weeks ago in my 182.

The DA was over 11,000 when I blasted off. I’ve never used more than about 2,000’ there for a 6,000’ runway. I’m always well under gross.

[malaise]

18. But AF 1 is flying all over the place n/t

Last edited Thu Jul 26, 2018, 03:34 PM - Edit history (1)

[Hassin Bin Sober]

35. I believe AF1 has some souped up engines with classified performance capabilities.

[jmowreader]

37. AF1 is also extremely light for a 747

It doesn’t haul freight or a lot of passengers.

[Hassin Bin Sober]

38. I wondered about that.

Not sure how much extra weight all the gadgets add.

[dixiegrrrrl]

44. But there is the added weight of Trump's ego. n/t

[The Velveteen Ocelot]

53. LOL!

Also, if most of the hot air is inside the airplane, is takeoff performance affected?

[jmowreader]

74. On the flipside of that...

The chilly reception Trump gets everywhere he goes is good for at least 2000 feet of density altitude.

[trof]

49. True

[MyNameGoesHere]

45. Math!

https://www.dauntless-soft.com/PRODUCTS/Freebies/TrueAirspeedCalculator/

[budkin]

46. At least climate change is a hoax!

Remember that Jim Inhofe snowball?

[Yavin4]

47. A Chinese hoax at that! n/t

[A-Schwarzenegger]

60. It's a mollecular spacing capacity issue

that's too complex for non-scientists to understand.

[milestogo]

72. or to spell, either

[dixiegrrrrl]

78. Hee heee

I see what you did there.

[A-Schwarzenegger]

73. Exxactly.

You must be a scientist.

[PoindexterOglethorpe]

76. I worked at DCA (Washington National Airport) in the 1970's.

At the time the main runway was 5,280 feet, a number that should look familiar to all of you. (An online search claims the main runway was longer, but trust me, back in the 1970's it was 5,280 feet long and has been lengthened since then.)

In the summer we often had to restrict loads because of the heat and reduced lift. In this approximate order we would leave off: air freight, air mail, baggage, passengers.

Sometimes we were told at the ticket counter to let the passengers know that their luggage might not be arriving with them. To say the least, the passengers were never happy to learn that. I don't recall that we ever had to leave passengers off, but back then flights were rarely full, which would have helped us.

And we're talking temps that was in the '90s, not as much hotter as it would be these days.

It will also make a difference just what type of aircraft is involved. I never recall the summer heat being a problem when the planes were a 44 passenger Fairchild, or a 69 passenger BAC-111. But a DC-9? That held 100 people. That was a bigger problem in the heat.

[dixiegrrrrl]

79. How much difference does humidity make?

Those of us who swim thru the hot humid summers swear the air weighs more than in the winter.

[PoindexterOglethorpe]

80. I honestly can't recall how much difference the humidity made.

It probably was a factor, but I simply can't recall, and I suspect that humidity really wasn't an issue.

The issue at DCA then was the length of the main runway. Others have posted good information above about how very long some runways are, especially in places that are often very hot or are at high altitude.