Also, let's not overlook the fact that your husand is 6' tall and 280 pounds, that is morbidly obese. If he could just drop 10 - 15% of his body weight he will see an improvement in his BP.
Good luck!
Jon
Another worry would be the fact that your husband is sitting for probably extended periods of time in the plane, and this plus high blood pressure is a worry for blood clots, eg., heart attack or stroke. I'd urge him to also get up and walk around in the plane as often as is possible.
Your husband should be treated for high blood pressure to avoid a heart condition. High blood pressure is responsible for damaging coronary arteries, and this damage can occlude the vessels, etc. and compromise the amount of oxygenated blood to the heart tissues. This can/will lead to heart failure, heart attack etc.
The nose bleed indicates the blood pressure is high enough to burst the vessels associated with the nose. This high blood pressure can burst the tiny vessels in the brain causing a major stroke.