Beware flying LL over glassy sea
AK,
I was talking to a serious twitcher friend of mine about this picture. He told me it's their standard method of sneaking up on prey. In lieu of a radio-altimeter, they use their breast-feathers as a GPWS!
I was talking to a serious twitcher friend of mine about this picture. He told me it's their standard method of sneaking up on prey. In lieu of a radio-altimeter, they use their breast-feathers as a GPWS!
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Step Turn wrote:
I think you're slightly over-dramatising it. With a little practice the transitions from ripple to glassy and back again can be managed by feel, and with eyes outside the cockpit there are often subtle height clues to be seen on a glassy surface:
The vital key is to recognize the sudden change to glassy, and begin to climb immediately. The light ripple you're flying over can become glassy in an instant if the gentle breeze ceases. When you fly from the rippled area, to the glassy area, there will suddenly be no way to judge your height, so you'd better be in the climb. Or, if in a seaplane, perform a glassy water landing.
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With a little practice the transitions from ripple to glassy and back again can be managed by feel, and with eyes outside the cockpit there are often subtle height clues to be seen on a glassy surface:
The subtle height clues are as often misleading as clues, and often are not at all there. The nature of glassy water is that it can go from "clues" to "no clue" in an instant, and at that instant you suddenly can't visually detect if you're going up or down. The same will occur over unbroken snow, which I was teaching during dual ski flying training last week.
When I am training water flying, or ski flying, upon arrival over a glassy or unbroken surface with no "shoreline" cues, the pilot will either continue in a "glassy water" landing technique (which cannot be power off), or they will begin a climb away, or, they will not be signed off. It's worth the over dramatization, and is not negotiable. I see it as being every bit as critical a piloting discipline as stall/spin recognition, as the stall/spin might happen with altitude and time to recover, failed glassy water/unbroken snow awareness very certainly will have zero opportunity to recover.
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The visual clues on glassy water can include flotsam, waterfowl (but see above), fish rising, and on a loch in a hydroelectric chain there's often some bubbles or scum.
ST, I don't train anyone, but you're right - we have to master the proper glassy water technique first.
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Gene Cernan, Apollo 17 commander, crashed a Bell 47 helo into the Indian River in 1971 while showing off for some boaters. Smooth water was cited as a cause in the accident report:
The crash almost caused Captain Cernan to lose his place in history as the "Last Man on the Moon":
Cernan's '71 Helo Crash
On October 18, 1971, a NASA press release stated that “misjudgment in estimating altitude” was the primary cause of the crash. The board listed possible mitigating factors which may have contributed to Cernan's failure to realize that he was flying into the water. These included a lack of familiar objects on the river surface to help him judge altitude, possible visual focusing on a false water surface because of the water's millpond smoothness and a change in sun reflection on the water cause by the change in course just prior to the accident.
The board also conjectured that Cernan's extensive experience with high-speed aircraft may have contributed to his altitude misjudgment. The thought goes: the lower a pilot flies in a jet aircraft, the faster the surface appears to pass by. The effect is not as pronounced in a slower aircraft such as a helicopter.
The board also conjectured that Cernan's extensive experience with high-speed aircraft may have contributed to his altitude misjudgment. The thought goes: the lower a pilot flies in a jet aircraft, the faster the surface appears to pass by. The effect is not as pronounced in a slower aircraft such as a helicopter.
James McDivitt, an Apollo Manager at the time, demanded that Cernan be removed from flight status and not be given command of Apollo 17, as the master Apollo manning plan called for. However, Cernan was defended by the chief astronaut, Deke Slayton, and given the Apollo 17 command. Upset by the decision, McDivitt resigned as an Apollo Manager shortly after the Apollo 16 mission in June of 1972.
Gene Cernan went to the moon on the final mission of the lunar Apollo program. Cernan became "the last man on the moon" since he was the last to re-enter the Apollo Lunar Module during its third and final extra-vehicular activity (EVA).
Regarding his 1971 helicopter accident: in later accounts, one of which was written by Cernan himself in an autobiography, it is revealed that Cernan was flying too low and showing off for nearby boaters. Cernan often describes the experience as "Mr. Toad's Wild Ride."
Gene Cernan went to the moon on the final mission of the lunar Apollo program. Cernan became "the last man on the moon" since he was the last to re-enter the Apollo Lunar Module during its third and final extra-vehicular activity (EVA).
Regarding his 1971 helicopter accident: in later accounts, one of which was written by Cernan himself in an autobiography, it is revealed that Cernan was flying too low and showing off for nearby boaters. Cernan often describes the experience as "Mr. Toad's Wild Ride."
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Basil, sorry to be so late to the party. But yourreminded me that I was on that squadron at that time. You might be interested in a bit more of the story.
Because of the wing dihedral, the Hastings' two inner engines were, I think, four inches lower than the outers. So four inches was the margin of error - and indeed the two inners did stop, with bent props.
Now, the Hasty-bird did not go well on two (didn't go all that well on three, come to that). But at the time they were North of Cyprus, not far from Kyrenia, and didn't have the fuel to get round the island to Akrotiri. Anyway, they were based at Nicosia. But the problem was, how to get over the mountains along the panhandle. They managed it.... just.
The captain was required to present himself for a no-coffee interview, which was closely followed by hearty congratulations for getting one of HM's valuable Hasty-birds back more or less in one piece.
airsound
Because of the wing dihedral, the Hastings' two inner engines were, I think, four inches lower than the outers. So four inches was the margin of error - and indeed the two inners did stop, with bent props.
Now, the Hasty-bird did not go well on two (didn't go all that well on three, come to that). But at the time they were North of Cyprus, not far from Kyrenia, and didn't have the fuel to get round the island to Akrotiri. Anyway, they were based at Nicosia. But the problem was, how to get over the mountains along the panhandle. They managed it.... just.
The captain was required to present himself for a no-coffee interview, which was closely followed by hearty congratulations for getting one of HM's valuable Hasty-birds back more or less in one piece.
airsound
I can't recollect who told me the tale - probably read it in Air Clues.
For every prang there must be quite a few 'nearlys'.
Well, actually, I know there are
Last edited by Basil; 30th Nov 2017 at 10:01.
