Weather Question
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Weather Question
I put on my anorak today, dug out the old Box Brownie, and headed into the Selkirk to Moffat valley in the hope of catching some low level action. I could only stay till 12.30, and saw nothing, but it was incredibly windy there today. Is there a wind speed limit at which aircraft are not allowed to fly at low level?
Last edited by Dan Gerous; 27th Feb 2008 at 19:42. Reason: Spelling
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Not really, unless its a heli into an 80 kt wind, or a tutor into a 120 kt wind. The limit tends to be ejection seat / parachute limits, which I think start at around 50 kts. Also affects sea state, when high seas prevent jet mates from getting into their single-man liferafts. It's hard enough in the swimming pool!
On top of what 6foot says, it would have been exceptioanlly bumpy at low level over the Lowlands, which wouldn't be much good for aircraft of any type - some aircraft types have a restriction in the Release to Service (or equivalent doc) saying "Routine flights should not take place in severe turbulence" or similar.
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So which helis have ejection seats? 
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I remember reading in one of Roly Beaumonts books about flying the TSR2 low level in the Welsh mountains. He was sitting there noting how smooth the aircraft was flying when the Lightning chase pilot called that he was pulling up due to the severe turbulence.
Generally, high wing loading = low gust response.
Anyone know what the F104 was like low down?
Generally, high wing loading = low gust response.
Anyone know what the F104 was like low down?
Yes there is a limit
It depends on your Group orders in the RAF. 50 knots at 2000' is a general rule for all and 35 knots (steady as opposed to gusts) tends to be a usual rule.
It's all to do with coming down in a parachute with 25 knots+ downwards speed plus 35 knots sideways motion, which would almost certainly result in many broken bones and probably death! Especially if you land on uneven ground or rocks!
Flying down valleys with strong wind tends to lead to a bloody uncomfortable ride depending on your jet. The Jag was fine because there was no real wing to speak of. The Hawk can lead to you losing teeth! God only knows what the F-15 must be like!
BV
It's all to do with coming down in a parachute with 25 knots+ downwards speed plus 35 knots sideways motion, which would almost certainly result in many broken bones and probably death! Especially if you land on uneven ground or rocks!
Flying down valleys with strong wind tends to lead to a bloody uncomfortable ride depending on your jet. The Jag was fine because there was no real wing to speak of. The Hawk can lead to you losing teeth! God only knows what the F-15 must be like!
BV
Last edited by Bob Viking; 27th Feb 2008 at 14:21.
Not really, unless its a heli into an 80 kt wind, or a tutor into a 120 kt wind
Most fast jets will stop flying below this speed for the reasons mentioned above, also with a heli you can always turn into wind to take off, fixed wing ac have to use a runway and have crosswind limits
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6 Foot - the Tutor's wind limit is 40kt as alluded to in previous posts due to parachute limits. Btw the old girl could still have 30kt groundspeed in a 120kt gale at Vno - not as impressive as the queen of the skies I admit! 
(Does 500 feet count as low level - me thinks not
)
(Does 500 feet count as low level - me thinks not
)
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RAF FJ Regulations - Daytime 35kts or Gusts>40kts at low level
Nightime 30kts or Gusts >35kts at low level
If no accurate reading a forecast of 50kts at 2000ft will preclude LL flying.
As already pointed out, the limits are based on the prospects of surviving a parachute landing in those conditions vice the aircrafts ability to fly in those windspeeds.
Nightime 30kts or Gusts >35kts at low level
If no accurate reading a forecast of 50kts at 2000ft will preclude LL flying.
As already pointed out, the limits are based on the prospects of surviving a parachute landing in those conditions vice the aircrafts ability to fly in those windspeeds.
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Thanks for the replies. The wind was forecast 30MPH+ (would that be about 26 Knots?) yesterday at Selkirk so I imagine it would be worse in the valley. Back in the good old days of slide film, I only ever used 100 ISO film, so if the weather was poor there was no point in going out, but with the digi able to change ISO's I tend to go out in a bit more rougher weather now.
Danny
Danny
I remember flying into an 80kt head wind with an underslung load down south. We seemed to be passing what was actually a small lake for hours. With a VMAX of 100kts IAS for the USL and an 80kt headwind, it was a long, long, long, long, long day.
