FlushVision
Premium Pilot
Agreed.Flush,
The H doesn't really care about a GPS signal when flown in Angle mode. It's more reliant on the compass and baro altimeter for general stability. Position hold in hover improves when GPS is good, of course. You only really need GPS for RTH and Smart mode. The closer the H is to the bottom of the bridge the greater the probability GPS signal will be blocked by the bridge. GPS does not penetrate steel and concrete worth a ****, and the bridge will have a lot of both. Simply "shadowing" the H from GPS signals by flying low between a bunch of tall buildings can occlude a GPS lock. Being 6 lanes wide the over head satellite view will be severely occluded, with only the satellites on the far horizons being able to providing any signal from the sides of the bridge. Just remember you'll be hand flying the bird in what will essentially be a "stability" mode, and slow the speed slider some to make control more manageable.
But all that steel that goes into building a bridge could have a detrimental impact on the compass. That coupled with the confined space (Photo did say that his inspection would have involved him flying ' as close to the underside as possible') would have made such a flight risky. Then there's the issue about the baro altimeter not being entirely accurate on the H that could possibly cause the aircraft to raise up some feet without any height input from the pilot.
In my book, there's far too many 'ifs and buts' to do with this flight and in my view a honest and properly done risk assessment would render the flight undo-able in any reasonable fashion...Without seeing his client's brief and only going off what Photo has said, I would refuse the job for sure.
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