Why cant certain helicopters take off when there is a high pressure system in the weather?

Question

i am refering to 2 new coastguard helicopters which have just been delivered to ???????? when they had that bomb scare on the rig last week these helicopters were required but were unable to take off

Answer 1

I don't believe that is true.  All aircraft have performance variations that depend on air temperature and pressure, and some older helicopters have dramatically impaired performance in hot weather (which is often associated with high pressure systems).

But "can't take off" would be taking it a bit too far.

Answer 2

Never heard of this myth... Look up Density Altitude. All airfoils create lift by taking advantage of the density of the fluid they are moving through. If the fluid isn't very dense it won't create allot of lift.

High pressure indicates sinking air (not fast), heavier air, clear sky's this sounds good for flying.

Answer 3

because helicopters don't fly, they just beat the air into submission. High pressure pushes down.

Answer 4

The following is NA to the coast guard and permit emergency supply, transport, or medical services to be delivered to isolated communities, where the operation can be conducted with an acceptable level of safety.

§ 91.144   Temporary restriction on flight operations during abnormally high barometric pressure conditions.

(a) Special flight restrictions. When any information indicates that barometric pressure on the route of flight currently exceeds or will exceed 31 inches of mercury, no person may operate an aircraft or initiate a flight contrary to the requirements established by the Administrator and published in a Notice to Airmen issued under this section.

Answer 5

good ?