Wake turbulence is one of those ever present threats that we’re all aware of but much too savvy to get caught up in. The most recent incident involved a Lear 45 on approach to Mexico City that crashed several weeks ago when it go too close to the Boeing 767 it was following. The last radar hit showed just over four miles separation when five miles is considered the minimum. The cockpit voice recorder transcript dramatically showed how quickly things can go from boringly normal to completely out of control in literally seconds. There were nine fatalities on the jet and five on the ground.
I’m personally not convinced that one mile further back would make that much difference – the main thing is not to be below the lead aircraft. Back in the late 60′s and early 70′s FAA did a lot of testing on the phenomenon. The test pilot comments should be sufficient motivation to absolutely avoid the big rollers.
Danger exists not only on arrival but departure as well. I once refused takeoff clearance at Atlanta’s Hartsfield airport when ATC wanted me to follow an MD80 on climb out. The Super 80 may be a pig, according to some who fly them, but a Bonanza will not come even close to out climbing one. I had asked for an immediate turn out which ATC refused, so I refused. Since I was in holding position on 9L and royally gumming up the works, the controller suddenly became reasonable and saw things my way. No penalty, no foul, just a need to understand the physics involved.
If you fly where the big guys roil the skies remember that distance, altitude (above) and alternate flight paths are your friends.
For a quick review, take the ASF quiz on wake avoidance.
Special thanks to pilot/photographer Steve Morris for the great wake picture.
Epilogue to last week’s blog on prop safety: A student pilot was was killed last week when he hastily departed a Cessna 150 flown by another student, upon fear of being discovered of flying illegally together. Note to self: Don’t fly illegally and certainly don’t attempt exit through a spinning prop.