You don't have to upgrade to a higher capacity (although that's not a bad idea.. ) you just have to insure that it is charged and ready to fly. One inexpensive device we've talked about quite a bit here on RCU is Voltwatch. They cost about 10 bucks or so at Tower Hobbies, work for both 4.8 and 6 volt packs, and will give you an instantaneous indication of your battery charge under load. Check it out. It plugs into either a vacant receiver channel or, with a Y cable, can connect to any channel. It is especially useful to check linkage for binding (the indicating LED's go from green to yellow to red indicating charge condition and, when moving the sticks, will show what channel is binding, if it indeed is). Binding will cause your battery life to quickly bleed off.

And, well, depending on how strong that wind is, you may or may not get it to land where you want it to in a dead stick situation, but it is best to try to get it pointed into the wind and get it down as quickly as possible. The obvious place for landing is on the runway, but often, you just don't have that opportunity. I've been there, so I can speak with experience. I've also been able to get it turned on final and landed on the runway.. maybe not in front of me, but at least on the runway. Our runway is about 3,700 feet long and about 150 feet wide so we have lots of room to land