Hot n' High - what to expect

[Hufty]

California beckons this summer and the school we're renting from doesn't seem to require a high elevation airfield checkout (at least if you've got over 100 hours).

This seems rather odd as I've heard all about the nasties of operating into and out of airfields with a high density altitudes so I was wondering if fellow Ppruners could offer some advice.

I understand it is mainly the poor take off and climb performance and increased groundspeed on take-off and landing that are the dominant issues, but having never landed anywhere high just don't know. Any advice will be welcome....

[FlyingForFun]

Hufty,

You're right, that does sound strage. Surely you could ask an instructor to check you out, even if they don't actually require the check-out?

Anyway, I did this checkout myself about 18 months ago, in Arizona. Wasn't all that hot, since it was winter, but definitely high. The most important thing is to check the performance figures in the POH. There's really no secret to it - if the manual says you can make it in with a safety margin then go, if not then don't go.

As long as you've checked the graphs properly, there isn't very much more to say about the actual take-off and landing. The groundspeed will be faster, but you should be used to varying groundspeeds anyway because the groundspeed depends on the windspeed even at sea-level - so it may feel like you have a small tail-wind in terms of your higher groundspeed. Personally, I didn't really notice this. Climb performance is only really an issue if you're taking off directly towards a cliff face - it wasn't something I worried about at all while I was over there, other than to accept that it takes a while to get to 10,000'.

The other thing you need to understand is mountain weather. Never fly towards a mountain unless you have a get-out plan in case of a strong vertical wind. Try to stay a few miles away from mountains, especially if downwind of them. As long as you stick to those two rules you should be safe.

Talk to local pilots as well as instructors. But the main thing is to stay safe, be cautious - and enjoy it!!!

FFF
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[Dufwer]

I would have thought that the most important aspect of hot and high flying would be to have a clear understanding of how to handle the mixture. Leaning for peak power before take off is not something that most UK PPL types would have any experience with. FFF, you have been-there-done-that, would this not be a reason enough in itself to get checked out on?

Regards
D

[FlyingForFun]

Good point, dufwer. If you don't know how to lean already, then you'll need to learn. Leaning for take-off is an interesting one, I was taught different things on different aircraft by the same instructors. Check the POH.

Also on the subject of engine management, remember that power and throttle position aren't the same thing. As you gain altitude, you'll need to open the throttle more in order to maintain the same power (assuming you've got a normally-aspirated engine). Expect to have the throttle fully open for cruise above about 6000-7000'.

Anything else I've forgotten?

FFF
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[stiknruda]

leaning is key

the engine develops less power hot & high

AND

the wing does not work as effectively.

Have flown a lot from 5 500' and plus 30 degrees.


Flew an injected Pitts from 5 500/plus 30 down to the coast. Sea-level still plus 30 - what a different aeroplane above the water!

Stik

[Sultan Ismail]

Hufty

Hot 'n High

A very important point, missed by many, the aircraft and engine are not the only bodies running out of air.

So are you, and if your normal flight levels are in the UK style 1500' then flying at 10,000' may upset your reasoning process.

High Plains and Highveld fliers, used to aerodrome elevations of 6000' are not too upset by flight at 10,000', but think about your body and get a local to come along for a couple of rides, just in case you forget something. You do acclimatize after a while dependent on your own state of health.


I can confirm that it is not unusual to lean for max (possible) power at takeoff.

Enjoy the experience

Sultan Ismail

[sennadog]

As has already been said, the POH should cover it and if it says you can (using the correct calculations) then you can.

The insructors I had in Nelspruit (2900amsl) and Jo'burg sounded a bit like Estate Agents with a different mantra - "lean, lean, lean" particularly not allowing yourself to get "hassled" by ATC whilst lining up and leaning yet again.

The guys at Lanseria were not at all keen on people having more than two up in a 172 and the one I flew in FANS felt a bit sleepy with three of us so be careful about the weight.

[Sensible]

Always fly in to a high and hot place with an instructor first. Things to remember are to read the book, lean on taxi, certainly lean for maximum power during run up and subsequent take off, lean during the climb too. Roll/descending air may be encountered off of adjacent mountains and actually experience descent during climb out. Don't ever assume that clearance will be certain over mountains or fly into blind valleys/canyons because of the danger from roll/descending air. You may need to circle to get out of low level terain over higher. You may need to search for the direction of climb to get best climb ie; you may find that the aircraft will climb best facing the direction of wind rather than the direction you plan on departing. Always, always, check weight and balance calcs. Check before you fly in that you can fly out having regard for weight/balance and length of runway/density altitude. Landing/take off may well be turbulent close to mountains.

[Tall_guy_in_a_152]

I agree about the importance of human factors in hot and high flying, even though I have never actually done it!

The South Western US is a favourite holiday destination of mine (fly-drive, but after all the recent threads I hope to fly-drive-fly next time!).

Sight-seeing around areas such as the Grand Canyon, Yosemite and Big Bear (7000 to 9000 ft asl) the shortness of breath after a jog from the car to a view point is really noticeable (OK, so I am not particularly fit).

The effect seems to be cumulative over a few days at altitude leading to tiredness, poor concentration and irritability (Mrs TG particularly prone to the latter :ouch: ).

Tall Guy.

[Hufty]

This is all great advice - many thanks. You're right - doing it with an instructor first is the best strategy to avoid any problems. We'll be 2 up with a modicum of baggage so will be right at max weight a lot of the time too.

Thanks all - this will all be added to my "things I need to think about to make best use of my hour-building trip in the US" list!!

[rustle]

One other thing to think about when hot and high is the increased turning radius - especially noticeable turning base-to-final when circuit height is same as you are used to in colder/lower places - you may find yourself needing to start the turn to final when the runway is at 10o/c rather than 11o/c... (LH circuit obviously ;) )

[Sensible]

rustle's point is very valid, also in the circling turns to climb out of canyons or valleys, anything other than very shallow turns can cause considerable loss of altitude.