On offshore platforms there are various things that get emitted that can affect helicopters. The sources can be deliberate or unintended.
FLAMMABLE GASES
You can get a release of flammable gas, possibly natural gas/methane or a mix of gases like butane and propane. Depending on how much and the conditions of the release, this can end up in a variety of places. If a helicopter flies into the gas cloud from such a release, the flammable gas will add to the fuel being burned in the engine. There are two possible undesirable consequences:
the turbine will/may run up out of control; and
the gas cloud may be ignited by the engine with unhappy results for both the hele and installation.
HOT GASES & AIR
Installations have vents that from time to time vent hot air or gas. Although this may not be flammable, it can affect the helicopter because the air/gas will be hot and less dense, reducing performance at critical stages of flight.
Gas/air releases can be from intended locations or unintended ones. The timing can also be controlled or uncontrolled.
FLARES
Flares are a means of getting rid of flammable gas "safely". The intention is to vent the gas at a safe distance from the installation. These days, the gas is meant to be ignited and burn as a flare: generally flares are now only used as a safety device to cope with process upset. They are designed so as to ensure that the levels of thermal radiation from the flare incident on people or equipment are not dangerous. However, if you end up in a place never envisaged by the designer or the rate of release is greater than planned you may be in trouble.
The other issue is turbulence created by the structure, but that is rather different.
Last edited by Helinut; 25th February 2007 at 16:19.
Reason: To correct typos