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heat waves

Jun 21, 2017

Recent heat anomalies up to 12C above ‘normal’

A warming planet poses issues for airlines that many players in the flying game might see as less pressing than aggressive competition, or the struggle to get on top of airport handling or navigational fees, or excessive or misguided regulations.

But this week heat grounded some regional jet operations in heatwave affected airports in the US, in an indication of what will inevitably happen where heat waves become more powerful and frequent than aircraft designers anticipated and begin to have increased operational consequences for larger capacity jets.

It’s technically a more complicated set of issues than set out in most general media reporting, although this New York Times report sets a far higher standard than the pack. (Apart from using the British colonial temperature scale, in some sort of obsequious historical throwback you can fix by just keeping a tab open for degrees F to C conversions.)

It might be helpful to try and reduce these issues to lay terms, at the risk of course of not being strictly or exhaustively accurate in the fine details.

In fact the challenges posed to big jets are already being taken very seriously by Boeing and its GE engine partner in the 777-X program because the overwhelmingly larger part of the orders for this family come from the Middle East or ME3, Emirates, Etihad and Qatar Airways, who all have global hubs that already fit into the ‘red hot’ category. (As well as being prone to fine dust concentrations that make engine washing and contamination control incredibly important to keeping their fleets reliable.)

The hotter the field temperature is the more the atmosphere ingested by jet engines expands, meaning the distance between molecules of oxygen increase, lowering the amount of energy an engine can generate by burning oxygen as it powers an aircraft toward takeoff speed. Hotter, lighter air mass also reduces lift.

That reduction in available power per unit volume of air means the jet takes longer, and has to therefore go further to reach a speed where it can generate enough lift to leave the ground and do so at a safe gradient capable of missing inconvenient obstacles like trees, buildings and terrain beyond the end of the runway.

It means that in some circumstances, the aircraft cannot conform with the safety requirements of a full load, which can be the case even on a ordinary day at airports like Wellington in New Zealand, with a fairly short runway anyhow.

If the jet has only two engines, which is true of most airliners these days, the rules require it to be able to take off safely after one engine fails at a speed which is too fast for it to safely stop before hitting the fence at the far end. “Safely” is defined as being able to climb above a certain height at a specified distance, and for the aircraft to have demonstrated during its certification phase that it remains controllable even under the provocation of crosswinds of a certain strength and so forth.

Slamming on the brakes isn’t a safe option if, as if often the case, the total weight of the jet is higher than the minimum weight at which it can safely land. Landings impose much higher forces on undercarriages than takeoffs. Get an aborted takeoff ‘wrong’ and the heat load in the wheels of the jet can exceed the point at which fusible plugs will deflate the tyres, likely creating a fire more than capable of igniting the full fuel tanks, which will rupture if they gut themselves on a ‘fence’ or ground equipment or beacons and so forth. All sorts of things can go wrong in a split second in a botched aborted takeoff, so the standard operating procedure above a certain speed is to continue the takeoff, ‘limp’ into the air, and loiter, perhaps assisted by a fuel dump mechanism, until the weight of the jet falls to a safe level for a landing, or even just an acceptable ‘overweight’ landing, which will require a subsequent detail inspection for airframe deformations and any repairs resulting from them.

But, big but, if the jet has three or four engines, the safety rules are less prescriptive, in that losing one engine doesn’t have as dire an effect on the aircraft’s ability to climb away from the airport, and the calculations for permissible loads in unusually hot conditions may allow it to avoid a payload penalty if taking off at what might even pass for a heat wave in Dubai rather than a more ‘normal’ field temperature for that part of the world.

A380s can take off in extreme heat conditions at Dubai without the same payload penalties as 777s, or A330s, because getting into trouble with three out of four engines working is a lot less problematical than dragging a dead engine with a much larger diameter into the air with only one engine working.

OK, engine failures on takeoff are rare, but not unknown. The incredible safety performance of modern jets is build on the foundation of insisting on certification standards that address risks that could otherwise result in massive casualties. Besides, no one has yet worked out how to design a viable giant twin engine jet airliner that could take up to 840 passengers, which is what you’d get inside an A380 if an airline tried to pack one as densely as some operators do their A330s, and 787s and 777s.

(One ends up with engine diameters so wide that the outer sections of the fan blades are rotating much faster than the speed of sound, stuffing up their efficiency by having to fight excessive drag.)

The nearest attempt to do this is the forthcoming 777-X, and the ME3 made it very clear to Boeing and GE that their purchase of the type depended on achieving new standards of extreme hot condition performances even though this impending big twin wide body will not have as much potential capacity as an A380.

In the New York Times article the much respected US analyst Bob Mann is quoted thus:

Robert Mann, the president of airline industry analysis firm R. W. Mann & Company, said that although airlines were working to become more efficient now, they were not doing much to prepare for the longer-term effects of climate change. “In a world where they’re focused on near-term issues, the glacial rate of environmental change is not within their fleet-planning horizon,” he said.

Airports are going to experience more heat waves. Even if the mean hot season temperatures average a rise of only one degree C or less compared to now, the distribution of days when the variation is 5C or 8C or even higher than that will become a huge nuisance for airlines and travellers.

Where it is physically possible, airports will come under pressure to extend runway lengths to accommodate weeks in which extreme heat would otherwise curtail the dispatch of fully loaded jets, or even prevent some departures.

Travellers have plenty of reasons now to get hot under the collar about the deliberate degradation of cabin amenity in all classes of carriage as toilets, seat pitch and cushion width are cut back because it makes short term performance metrics (if the extra capacity is sold) look good.

Add to this the self-inflicted stupidity of ignoring the long standing need to curb fossil carbon releasing sources of energy, and the shambles that is mass air transport today is going to become even more discouraging.

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29 comments

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29 thoughts on “Global warming begins to burn a hole in air travel

  1. George Glass

    Its difficult to know where to start.There is so much wrong with this story.The daily routine of any pilot is , after flight planning and grabbing a cup of coffee, is to proceed to the cockpit and set the aircraft up for departure.A critical function that must be performed is to calculate take-performance,usually done these days by an App. on an Ipad or similar.The object is to determine the minimum (minimum!)thrust required for take-off.Obstacles,engine failure etc. are all accounted for.It is almost always NOT temperature limited. Reduced thrust take-offs using the assumed temperature of 40 degrees plus are the norm.Worst case at a port like Melbourne max. thrust and full length will do it. Hot and high with a short runway might be the occasional exception.Sorry Ben,this is a bad case of confirmation bias for those with hightened anxiety about climate change.Current engine technology is easily capable of coping with a couple of degrees temperature increase.

    1. TomTom

      “It is almost always NOT temperature limited.” But that’s what this story is about, days in which there are temperature issues and how it affects aircraft/airlines/aircraft. It is certainly a valid discussion.

    2. derrida derider

      Like a lot of people, George, you miss the point about (say) a 2 degrees average warming. Weather follows a Gaussian distribution. If the summer average daily max at Doha is (say) 38 degrees, and the average increases by 2 degrees to 40 degrees, the number of days in a year where it reaches 50 degrees does not go up proportionately – it will easily triple or quadruple (depends on the variance).
      This mathematical property of a Gaussian distribution is actually one of the many, many ways we know the planet is warming. Pretty well every year some place in the world have a record high while some other place will have a record low, but the about 5 times as many record maximums are now being observed as record minimums.

  2. Ben Sandilands

    George,
    If you read the reports it’s not about a couple of degrees at all. In the case of the US airports its about an extra 11C. If you prepare your cockpit with the same inattention to detail we ought to be worried about what might happen, although I hasten to add I’m sure you fly more carefully than you digest inconvenient truths from the world at large. The thing that is wrong about the current situation is a nothing to see here just move along attitude. It’s not good enough. Tell us if you have a moment or two to spare, what is actually wrong with the NYT report and how it is that the airports concerned and everyone else has overreacted. And why Boeing and GE and their major ME customers really needn’t bother going to all the trouble they have in relation to the 777-X? Please.

    1. TomTom

      45C is springtime in Dubai these days; 50C+ is seen regularly. At least we’re at sea level but, still, those of us who live and work there, or fly to or through there, have to deal with the myriad effects of the heat. Of course it’s an issue.

      1. Jacob HSR

        What was the springtime temperature in Dubai 10 to 15 years ago?

        1. ghostwhowalksnz

          Airports are hotter as they have sq miles of concrete

  3. TomTom

    Not to worry: at the rate we are going, we will not require flights to warm destinations, anyway, because we will all already be in one.

  4. ghostwhowalksnz

    Hot ? Airport closed ? Thats what happened back in 1990 too, and the hottest ever recorded temperature in Phoenix , 122.
    But the reason the planes were restricted during the peak temperature period? The flight manuals didnt go above 120 F
    The manuals/ software have changed now but the temperature the other day didnt even get over 120 let alone get to 122

  5. ghostwhowalksnz

    ” the total weight of the jet is higher than the minimum weight at which it can safely land.”
    Its a bit misleading to say a plane cant land at its takeoff weight. The most common reason for a lower weight- where possible- is just the landing configuration during approach is not as stable. As for the undercarriage, an engineering check isnt the end of the world, just time and lost revenue.
    Part of the certification is a rejected takeoff at maximum weight, so it can be done,
    with no thrust reversers, and ‘worn brakes’
    Wikipedia puts it more clearly-
    “Small brake fires are acceptable as long as they do not spread to the airplane body within five minutes (the maximum likely time for arrival of the airport fire fighters)”

  6. ghostwhowalksnz

    I looked at your isothermal map, the time period is a week with the base temperature
    from the average during the same week over 40 years, 1961-1990 [ The base time period for climate studies is 30 years so should be say 2015- 1985]
    eg Melbourne in the middle of the ‘max anomaly’ area for October has an average low of 10.6C and average high of 20.1C so giving difference of 10.5C between max and min
    12C doesnt seem that much as an anomaly, especially when its been cherry picked.
    The record temps for Melbourne in October is 0.1C and 36.9C

    1. Ben Sandilands

      The point of this post is that unusually high temperatures are interfering with airline operations, and the risk they will continue to do this to a greater extent is well supported by the issues discussed in the NYT article. The graphic was chosen for purposes of decoration rather than content because yours truly couldn’t find a Commons licence or copyright free photo of a heat stressed jet or a terminal full of sweating passengers.

      1. Goat Guy

        Ben,
        I lived in Alice Springs in the 80’s. It was common in summer to see the jets sitting on a taxiway waiting for the temp to drop later in the day. There were always delays as a result of the combination of extreme heat and altitude and I have many photos of a (small) terminal full of sweating passengers, particularly as there was no aircon.

        1. Mark Skinner

          Yes, there were. The point is that with global warming, there will be more heat based delays. How many more is the pertinent question.

  7. Roger Clifton

    Arid locations that heat up quickly between dawn and midday also cool down quickly between sunset and dawn. For example, the difference between maximum and minimum temperatures at Alice Springs today is 20° C. In this case the low temperature is 5° . That is the temperature at the Stevenson screen, so it is the temperature of the inversion layer, which surely must be deep enough to achieve lift off. During high summer, such destinations may prefer to lift their curfew for nighttime takeoffs than lose tourist traffic.

    Ironically, climate change is increasing the humidity of the night sky everywhere, so heat is increasingly less able to escape during the night. Minimum temperatures are increasing faster than the maximum temperatures.

    1. ghostwhowalksnz

      ‘climate change is increasing the humidity of the night sky everywhere’
      Where are they saying that ?
      The computer models require the amount of moisture in the air to increase as this is the largest ‘greenhouse gas’, the amount of CO2 is orders of magnitude less. Yet to see the % humidity collected on a global scale to show this is happening now. However this could be happening on a very small scale

      1. Ben Sandilands

        Ghost,

        The issue is fossil locked carbon dioxide because it is the enduring long term regulator of the rate at which the atmosphere can shed heat into space. Unlike water vapour, which is rapidly created, absorbed, precipitated and otherwise recycled, the CO2 processes involve dwell times of thousands of years in terms of being reprocessed into olivine, or corals or other materials. These natural carbon cycle processes, and the at times geological timescales in which they function, are being overwhelmed by the industrial liberation of fossil carbon at an incredibly rapid rate that nature cannot deal with before they wreak havoc on the marine food chains, and the retention and feedback consequences for heat build up in the seas and land.

        Some scientists argue that to correct the current situation we need to devise processes that will ‘scrub’ excess carbon dioxide levels within human life times. Which may prove to be the case, although there would be devastating unintended consequences if the extent to which that excess CO2 was removed lacked ‘kill switches’ or means to prevent the removal of most unbound CO2 in the environment.
        What worries me is that many politicians and environmentalists and ‘deniers’ argue their cases in a state of total ignorance of the true nature of fossil locked carbon, the roles it plays in natural and industrial situations, and the challenges its management and reduction will involve.

        However the simplest, but most imperfect remedy, is for us to devise competing forms of energy generation that shut down the excess liberation of fossil carbon by being cheaper to use. That process is already underway in terms of solar storage technology becoming more available as a means of undercutting the coal based power generation, and even encouraging people to quit the grid, and seeing banks refuse to lend to new fossil fuel projects.

        1. ghostwhowalksnz

          perhaps Ben you should study the definition of climate change. Here it is to make it easy
          ““Climate change. Climate change refers to a change in the state of the climate that can be identified (e.g., by using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer. Climate change may be due to natural internal processes or external forcings such as modulations of the solar cycles, volcanic eruptions and persistent anthropogenic changes in the composition of the atmosphere or in land use. ”

          No one here has offered any changes that have lasted decades or more- they are happening of course.
          Looking at this week in Phoenix or that week in Australia Oct 2015 is weather not climate.

      2. Roger Clifton

        Ghost – meteorological evaporating pan measurements have been decreasing (for 50 years!) despite rising temperatures. The cause is ascribed to a decrease in solar irradiance in the water absorption bands. That is, those wavelengths have already been absorbed on the way through the atmosphere, implying increasing humidity.

        The water is in the troposphere, almost by definition. High in the too-cold stratosphere, the dominant greenhouse gas is CO2 not H2O. It is from these high levels that much or most of the re-radiation to space occurs.

        1. ghostwhowalksnz

          ” The cause is ascribed…” ‘Implying increasing humidity”… good to know they are using evaporating pans ???.

          Direct measuremnt of humidity have been made for donkeys years, surely there are 30 year empirical values known, like you are supposed to have with …you know.. Climate.

          Please, it makes it easier to know what terms are and are able to say ‘dont know’ when claims of night time humidity increasing globally are made.

  8. Jaeger

    On the bright side, global warming might force the bean-counters to revert to habitable seat widths/pitch for the weight savings.

  9. comet

    A story like this always excites climate change deniers to come out of the woodwork to criticise it, often for other spurious reasons.

    There are many religious people who accept the science of climate change.

    But on the political level, it’s interesting that the politicians who are climate change deniers are always devoutly religious.

    Think about it. Hanson, Roberts, Abbott, Abetz, Dutton, Trump… the list could go on and on.

    The same people want to sever the communication of science to the public, whether it be cutting the budget of the CSIRO, threatening the national weather forecasting bodies (Abbott and Trump), or cutting funding to the ABC and installing a like-minded chief who has the aim of reducing the coverage of science news.

    It’s a war against science going on here, and therefore a war against rationality and free thought.

    1. ghostwhowalksnz

      Its just weather Comet, not climate. Phoenix temperature wasnt even a ‘record’… yawn

      1. Ben Sandilands

        Ghost,
        You clearly know more about the issues than those pants wetting imbeciles in the airlines in the US, or the scientists, or those interviewed by the NYT. We don’t need to do f*ck all really do we?
        Then again, they may know what they are talking about, and it may well be an issue that will continue to force itself on us.

      2. Dan Dair

        Ghostwhowalksnz,
        It is now almost totally accepted that the planet is warming up.
        (If you choose to go against the grain, that is of course, your prerogative)
        The dispute is only about whether it’s a natural cycle, a man-made problem, or some combination of both.?

        Irrespective of which version of events is the most accurate, the facts are that the planet is warming up & the problems faced by the ME3 at their home bases & the much-publicised problems at Phoenix are just the start.

        In the future, days like those are going to be more common for pretty-much all of us who’re already in warmer parts of the world.

        Aircraft manufacturers are going to have to have a serious think about how to remedy this problem,
        & it’ll be a lot tougher to solve than the difference between using Summer & Winter tyres on your car.?

  10. comet

    There’s also the issue that climate change will result in rising sea levels that will render many of the world’s airports unusable.

    Recent modelling shows Brisbane airport will be one of the first to be underwater. The former Eagle Farm will turn into a fish farm!

    1. Dan Dair

      Are there any saltwater crops which could be planted, during the first few years that the airport estate becomes marginal wetlands.?
      #Turning a problem into an opportunity.?

      1. Dan Dair

        As soon as I pressed ‘reply’
        it occurred to me of the irony that the estate of the ‘former airport’ at Brisbane, might be ideal for growing a biomass crop which would be excellent for converting into aviation fuel for the airport,
        if only it wasn’t underwater now.?

        1. Dan Dair

          Seaplanes don’t draw much draught, do they….? Ben, you know stuff like that.?
          How deep would the water need to be at Brisbane, before seaplanes could land on the existing runway/s using the approach-light system & then taxi or be towed up to utilise the facilities of the existing terminal.?

          Where are Pan-Am & their ‘Clippers’ now that we’re going to need them all over again……?

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