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On sectional charts you can see that, through various restrictions, regulators encourage pilots to avoid flying too close to Gas Venting Stations. These seem to be places where natural gas may occasionally be vented into the air (for example from pipelines). I have been unable to determine if the gas is preignited.

Is the principal risk from gas discharge that's being mitigated here:

  • aerodynamic
  • explosive/thermal
  • respiratory
  • a combination of the above?

Have incidents occurred relating to these risks?

You can find some talk of the risks online but it seems mainly to be in the form of "My mate told me...".

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    $\begingroup$ Can you provide an example? $\endgroup$
    – Ron Beyer
    Commented Jan 6, 2020 at 20:52
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    $\begingroup$ 49 examples on this page: look for GVS. aurora.nats.co.uk/htmlAIP/Publications/2020-01-02-AIRAC/html/… $\endgroup$
    – Dan
    Commented Jan 6, 2020 at 21:55
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    $\begingroup$ I'm not sure why whether it happens in the USA or not is particularly relevant, but if it's UK-specific that's a fair point. $\endgroup$
    – Dan
    Commented Jan 6, 2020 at 21:58
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    $\begingroup$ There's a comment by the Kidderminster GVS that says "Strong thermals, smoke and gases" which may be a clue as to the nature of the hazards. $\endgroup$ Commented Jan 6, 2020 at 22:00
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    $\begingroup$ It's not UK specific. I've seen similar warnings on Dutch approach plates, and I am sure other countries have them too. $\endgroup$ Commented Jan 7, 2020 at 17:53

2 Answers 2

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Gas venting stations sometimes release natural gas at extremely high pressures, so there is a risk of strong updrafts or turbulence. In any case if you fly directly over you may be going through a cloud of combustable gas which could possible ignite. It's a low risk, but given it's rarely a problem going around them it would be my advice to do so.

I've flown over one without realizing and it put me in a 1200ft climb, I had to cut throttle in a hurry and dive to stay out of the London TMA. After that I paid attention to them.

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    $\begingroup$ That sounds surprisingly violent. May I ask which aircraft you were flying and at which altitude? $\endgroup$ Commented Jan 7, 2020 at 17:54
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    $\begingroup$ It was in a Cessna 152, IIRC 1800ft in VMC. It wasn't particularly violent, but I felt it. By the time I figured it out i was about 200 feet below a class A. $\endgroup$
    – GdD
    Commented Jan 7, 2020 at 18:13
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Since you want something beyond "My mate told me...", look no further than the UK AIP ENR 1.1:

5.3.3 Gas Venting Operations

5.3.3.1 Severe turbulence and power fluctuations in turbine engines could be experienced over gas venting sites during venting of natural (methane) gas under high pressure. Locations of gas venting sites are listed at ENR 5.3.

HTH.

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