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An aircraft POH generally gives a maximum demonstrated crosswind component but I have not seen any indication with regards to maximum gust component.

I understand that one is supposed to increase the approach speed by half the gust component but I'm not sure if there is a limit to the gust component above which operation becomes unsafe.

Example: imagine a GA aircraft with a typical takeoff speed of 60 kts, approach speed of 70 kts. Runway is 27, wind is 270 degrees at 20 kts. What would be the maximum gust speed along the runway to operate in safe conditions?

Note: this other question is similar but focuses on crosswind component.

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    $\begingroup$ Ya, the maximum headwind component can not exceed VNE! $\endgroup$ – jwzumwalt Jan 3 '18 at 20:56
  • $\begingroup$ @jwzumwalt if the wind really is 100 KT and you land at 100 KT, I suspect the turbulence and wind shear will probably put you upside down before you touch down! $\endgroup$ – assylias Jan 4 '18 at 13:18
  • $\begingroup$ This is really not to far fetched. Alaska often has high steady winds for many days at a time - 40-60mph is not uncommon. 3 or 4 days long is normal but 5-7 days is not rare. $\endgroup$ – jwzumwalt Jan 4 '18 at 14:58
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This is quite similar to the linked question but does have some differences. Gust components while reported differently are still part of the crosswind component. In other words a reporting like

Rwy 03, wind 090/25 gusting 40 kts

Is another way of saying the wind is holding at 25Kts and could be as high as 40Kts at times while you are on approach. In other words you may have a 25kt cross wind on touch down or you may have a 40Kt cross wind. Generally speaking gusts occur in the direction of the wind. In some cases gusty days also come with shifty wind conditions which add for a whole new element of fun.

The maximum gust component is not quoted in the POH because there are to many inconsistent factors that may effect it. The main one being the duration of the gust. A short gust well in excess of your crosswind maximum may be recoverable while long gusts in excess of your crosswind maximum may be unsafe. Strictly speaking a loose limit would look something like

(maximum reported crosswind) + (gust wind * gust time) > cross wind component

but gust time is not reported and thats a lot of trig to crunch on the fly so no limit is typically given. I have landed a Piper Archer in conditions gusting in excess of 40Kts safely but the wind was no more than 20 degrees off the runway.

Eventually you just run out of control surface...

Example: imagine a GA aircraft with a typical takeoff speed of 60 kts, approach speed of 70 kts. Runway is 27, wind is 270 degrees at 20 kts. What would be the maximum gust speed along the runway to operate in safe conditions?

In this scenario, with the wind down the runway, your maximum gust component is 50Kts. Above that and at your 70kts approach speed you would be moving backwards across the ground making it quite hard to reach the runway and potentially difficult to land the airplane if a gust were to occur at a low altitude. Most trainer aircraft like the one you describe cant do better than ~120Kts so 100Kts is about your gust limit otherwise its going to be hard to get to the runway.

NOTE: Gusty conditions (in my experience) are also generally accompanied by turbulence and in bad cases, wind shear. In many instances all of these factors combined can make an approach unsafe or un-flyable.

There is also an interesting discussion on it here.

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    $\begingroup$ Your approach speed doesn't matter. If the wind is 100mph and my cruise speed is 100mph then I can do a no flap vertical landing like a helicopter. $\endgroup$ – jwzumwalt Jan 3 '18 at 20:59
  • $\begingroup$ @jwzumwalt very true, I have edited to reflect. $\endgroup$ – Dave Jan 3 '18 at 21:23
  • $\begingroup$ Thank you for your answer - the bit I'm really interested in is your note at the end: yes in theory I could land in 27020G90KT with a 110KT approach speed but I suspect the turbulence generated by such wind and the high speed will make the approach and landing quite rough, if not fatal on a small aircraft. And the passengers will probably be puking all over the place :-) So I asked this question to try to find out what a reasonable limit is. If you could add a line or two on this it would be great. $\endgroup$ – assylias Jan 4 '18 at 13:14
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    $\begingroup$ @jwzumwalt What happens in those conditions the moment you shut down your engine(s), or even reduce power from what's needed to maintain a 100 mph cruise? $\endgroup$ – a CVn Jan 4 '18 at 13:45
  • $\begingroup$ @Kjörling This is really not to far fetched. Alaska often has high steady winds for many days at a time - 40-60mph is not uncommon. There are occasional accidents where a Cub or Luscomb with a 80mph cruise run out of gas trying to make headway in a 55mph wind. I landed my 172 once in a 35mph wind - 5mph slower than my stall (1 person and low fuel). The airplane lifted off the ground twice while I taxied. Fortunately my tie down was into the wind and a couple pilots saw my predicament and tied the airplane down while I was at the throttle. $\endgroup$ – jwzumwalt Jan 4 '18 at 14:53

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