Originally Posted by
Dexta
After a relatively quick (2 hours) search of the regulations, all I could find to determine VFR conditions and if it is legal to take off for Day VFR is as follows;
1. Forecast - If you can obtain a forecast then cloud must be at least 1000' AGL above the highest obstacle 10nm either side of track
If no forecast then pilot is satisfied that the weather at the departure point will permit the safe return within 60min.
2. Alternate - The forecast cloud must be Scattered or less, 1500' AGL and 8km vis (not applicable if less than 50nm)
3. Takeoff/Enroute/Landing - Class G: below 10,000' - 1000' vertical, 1500m horizontal, 5km visibility. AT or below 3000' AMSL/1000'AGL; clear of cloud and in sight of ground or water, 5km visibility - MUST HAVE a radio and used on appropriate frequency.
4. Reg 157 may fly below 500' due stress of weather.
For IFR the take-off minima is black and white, but for VFR it can be down to interpretation; for example, lets say there are no TAF's for my departure, destination or any airfields along my track. The ARFOR that I have obtained shows cloud above 1500' and visibility of 8km. However at my departure the cloud is low and I estimate that it is 800' and I guess visibility to be 5km and I'm satisfied I can make a safe return. I do not need an alternate due to forecast. I jump in the plane and take off. At 600' I start entering cloud, I drop to 500' and can see the ground and if need be due to press of weather I can fly less than 500' if I need to so I head off to my destination. Have I broken any Visual Flight Rules?
Please provide references to any rules that have been broken.
Dexta:
How do you "start entering cloud" as well as "remain clear of cloud"? You're IMC, not VMC, as soon as you "start entering cloud". Breach of 172.
The exception in 157 to which you referred says in whole: "through stress of weather
or any other unavoidable cause it is
essential that a lower height [than otherwise required by 157] be maintained".
The weather-induced stress has to be "unavoidable" and it must be "essential" that the lower height be maintained, before the exception applies. That is
not a blanket authority to take off and fly from A to B at 490' AGL just because the cloud base happens to be 500' AGL along the track from A to B.
Unless ISIS has overtaken A or the only source of your urgently-needed life-saving medicine is at B, you can avoid the weather-induced stress by doing a 490' circuit and returning to land at A. It's not essential for you to continue to B. If there's a suitable landing area in between A and B, you can avoid further weather-induced stress by landing there. It's not essential for you to continue to B.
I can sorta understand the decision to take off in the mistaken belief that the cloud base is much higher (although VFR pilots should acquaint themselves with the various simple methods of accurately estimating the height of low cloud bases), but as soon as you know the cloud base is going to force you below 500' AGL I reckon a decision to continue to your destination below 500' AGL would be dangerously irresponsible and in breach of 157, except in the sorts of remotely possible situations I've given. Even in those situations, technical compliance with the regs won't stop you colliding with that stonking great tower on the hill directly on track.