Usually only applicable this in airspace when you are >3000ft, (but below 10,000ft) Requirement to maintain 1000ft above and below clouds, 5km forward visibility and 1500m horizontally away from clouds. Owing the prevalence of controlled airspace, VFR on top is often only an option on longer transits over large bodies of water (e.g. English channel crossing pictures above ) or over some low level hilly/mountainous terrain where being above and well clear of any cloud is safer than attempting to navigate visually low level in undulating terrain. VFR on top cannot be flown under commercial air transport rules.

In the USA, ‘VFR on Top’ clearance means something different- it is a form of IFR clearance that once you have climbed through a layer of bad weather, you can then request 'VFR on top', which gives you more flexibility. To fly VFR on top, you need to have an instrument rating, be on an IFR flight plan, and be in an IFR capable helicopter.

FAA 'VFR over the Top'

The FAA alternative to flying VFR over a layer of cloud is ‘VFR over the top’. Like the European rules, you have to comply with the minimum safe separation, 2000ft horizontally, 500 ft below vertically, and 1000ft above from cloud, plus 3 miles of visibility in most cases. This AOPA article provides some good points to consider before embarking on VFR over the top.

Inadvertent IMC - Helipaddy

Updated 02/11/23 Link to EASA Night IMC video and Bruce Webb practical advice if you enter IIMC

What is it, and why is it so dangerous?

“U.S. accident statistics reveal that a helicopter pilot who unintentionally continues VFR flight into IMC will very likely lose control of their aircraft and be dead within a median time of 56 seconds“
Nick Mayhew- US Helicopter Safety Team

Introduction – What is IIMC?

Instrument meteorological conditions (IMC) exist during times of rain, low clouds, low levels of ambient light and or reduced visibility, and are often referred to as a ‘degraded visual environment’.

Different states have different legal definitions, e.g. UK VFR rules permit VFR flight as long as you ‘Remain clear of cloud with the surface in sight and in flight Vis >1500m below 3000ft (less than 140kts!) ‘

Inadvertently entering IMC remains one of the most dangerous and prolific cause of fatal helicopter accidents, which has claimed the lives countless of private and professional helicopter pilots alike. When a pilot loses visual reference to the ground, it can be difficult to maintain control of the helicopter, especially in a light, single engine helicopter without any form of stabilization system (e.g. stability augmentation system – SAS, or Autopilot). This can lead to a loss of control and an often fatal crash.

So, in this article we will explore why IIMC can be so deadly, how you can avoid entering it, and finally, when the chips are down, techniques you can use to safely deal with IIMC, if you unfortunately find yourself in this situation.

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Inadvertent IMC

What is it, and why is it so dangerous?

Introduction – What is IIMC?

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