Here's the scenario: You're at 10,000 MSL and your engine fails. You are at the black dot in the center of the picture, on glide speed, and exactly 17 nm from two airports. Airport A is to the North, and Airport Z is to the South. Both airports are at Sea Level. Winds are from the North at 10 KIAS, and constant throughout all altitudes. We also are presuming a perfectly held glide speed for best L/D MAX for entire profile. Yes this is a hypothetical situation, but it brings about a good discussion and some good key points to remember and train for.
For those that don't know, the Bonanza glide ratio in feet per nm is 1.7/1,000 feet. That is a nominal clean Bonanza, on speed will glide 1.7 nm for every 1,000 feet of altitude.
So in the case above, IF THERE WAS NO WIND, theoretically, the engine out airplane could make it to either airport. But as with real life, we have winds to contend with.
Given our scenario, and winds... Which airport to do you choose?
Knowing our glide performance and ratios, you might be tempted to pick Airport A, that headwind might help you "float" or stay aloft longer. Maybe??
Well, this is simply not true. The gliding airplane will perform the same throughout the glide profile and and airmass, and the headwind component will simply slow your ground speed and you will land short of Airport A. Your TIME in the glide will remain the SAME as if you were in a no wind situation. With headwinds, your ground speed will suffer, and you will not reach Airport A.
By the way, how far short would you land if you went to Airport A?
That's easy! 1.7 nm
Remember, that for every 10 KIAS of wind through 10,000 feet of altitude will reduce your glide RANGE by a factor of your glide ratio per nautical mile. So for the Bonanza at 1.7nm/1,000' ... you will land precisely 1.7 nm short. This of course assumes a perfectly held indicated airspeed for the weight of the aircraft, and perfect 10 KIAS of headwind all the way down. Not very realistic, but an interesting relationship none-the-less.
So that leaves us with Airport Z.
Airport Z is your best option. The wind will "push" you there faster and theoretically you would arrive 1.7nm "early" due to our above math relationship. That equates to 1,000 feet of altitude in the Bonanza. Perfect to set up your energy for a Low Key or Base Key downwind entry for a 180 degree turn back to the north and a nice touchdown. So you'll arrive overhead Airfield Z at 1,000 AGL. Make sense?
Key takeaway: Always consider ALL available surfaces to land, keeping in mind that all surfaces that reside in a "downwind cone" from your present position will be better options than ones that force you into fighting headwinds through the glide. When touching down (engine out), if at all possible, it's always advisable to land into the wind to slow that groundspeed and reduce impact forces.
See more discussions like this one in Engine Out Survival Tactics, available in paperback or eBook.