Originally Posted by pirol

Hi everybody,

during the summer months bushfire accumulates in California, Canada and Mediterranean Europe.

For me as a retired professional pilot its interesting to get more infos about influence of different flue gas, high temperatures over bushfire and less oxygen which dominates in those areas.

In 1974 in Germany we had an fatal helicopter accident overhead an hugh chimney which was investigated by officials. They found out that the mixture of „air“ over that chimney had 5% oxygen, 6% water vapor, 79% azotic air and 10% carbon dioxide. The investigated air temperature was 132 ° Celsius. The engine flame - out was mandatory.

Of course fire -fighting helicopter or fire-fighting airplanes are only a little time inside of those environment parameters, (I guess not more than max. 20 seconds) but long enough to be influenced by high temps., flue gas and so on.

The follow-up of parameter like reduced oxygen, high temps, loss of engine power and threat of crews due to smoke and gas are mandatory.

But I don´t know how high these things influence the real flying of fire-fighting aircraft. Is there anybody who´s able to give me more info about these special theme ?

Thank you in advance

Gert, Germany

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they suffer the same effects because the atmosphere is super heated from combustion and becoming thinner due to the heat reducing the atmospheric pressure near ground level, the flames of course are following the oxygen available continously at 14.28 PSI rising in height until it and the fuel is consumed.

high temeperatures affect an airplane or helicopters ability to attain or maintain lift due to the atmosphere becoming thinner and then gravity has an increased effect.

The helos rotary wing is still trying to push through the same amount of atrmosphere regardless of its density and load bearing ability and if the air is thinner close to the ground trouble insues if the pilot is to low.

Of course a helo with 4-6 or more rotors has better stability but physics still apply

as very hot thin air has less lifting ability,

The mid air break up of firefighting aircraft has always been an issue for me simply due to the rise in the surrounding air temperature and its becoming thinner due to same.

There a continous debate about a fire fighting aircrafts worthiness due to stresses and age-buuuuut one must examine the effect of thinner air upon any operating surface simply because the airfoil has less resistance to overcome and gravity still applies in my opinion.

with an airfoil knifing through that hot air which is thinner due to the heat the stresses are multiplied in my opinion due to less atmosphere near ground level and heat from combustion and its actual load bearing ability.

I would contact our nation weather service here in the united states and the usda

for the US forest service to learn more.

lzaharis ■