Performance Considerations

[Okavango]

If you apply the usual recommended factors for surface & condition/slope/density alt along with factors required for UK Public Transport ops (generally x1.25<TORA for take-off and x1.42<LDA for landing), it would preclude use of a lot of your regular GA airfields. My general approach has always been to assume MTOM and nil wind (partly conservative and partly to simplify things). As an example, with my approach I've regularly used an airfield with TORA of 520m where commercial ops would require in the worst case 740m (landing on wet grass in low pressure/high temps). I've never felt particularly risky in ignoring commercial ops factors though what do others apply and can it affect your insurance in any way?

[172driver]

Density Altitude. While this is generally not a factor in the UK (low-lying, pretty close to ISA standard temp most of the time), it is a BIG factor when flying in hot and more importantly hot-and-high situations.

In Europe, pretty much the only places you'll encounter a real performance degradation would be southern Spain in summer, when temps can reach 45C+ in the shade. I once took off from Seville in a standard C172 on such a day - the ground roll was amazing :E Luckily LEZL has a TORA of something like 11000 ft......

Once you get further south (incidentally to the area of your username!), then things become more complicated. Many strips in southern Africa are usable for t/o by SEPs in the early morning only during summer months, as you now have an elevation of 4000 to 6000 ft, high temps plus gravel/sand. Most definitely time to get out the POH and have a really good look at it! Same, of course, goes for the southwestern USA.

Quite a few 'lowlander' pilots have come to grief in the above areas.

[iwrbf]

Hi,

keep in mind that the given values for takeoff and landing are what experienced test pilots on new material achieved. The regular hobby spam cam driver in his worn out material will never come close to these.

I would like to add that there are more places in Europe than spain where one can see an impact on performance whilst taking off or landing. There are a lot of airfields with 1000-1500 feet ASL, add low pressure and 30 deg C in summer... you get the trick?

I would always calculate the correct distances and performance. And I would always add a safety margin of x percent for worn out engines and airframes and x percent for me not being a test pilot.

Kind regards,
Peter

[Genghis the Engineer]

When runway length starts to look a little marginal, I do do those calculations, and on occasion it has informed by ability to carry pax or extra fuel.

Where I'm flying a C152 from a 1000m runway, no of-course I don't.

As a quick check I tend to use the GASCo quick reckoner, printed on A5 and kept at the back of my kneeboard. If it's more marginal than that, I get the manual out.

http://www.gasco.org.uk/upload/docs/2005_1_Flight%20Safety16-18.pdf for those who haven't met it.

G