Piloting an airliner in freezing temperatures, a blinding snowstorm, and the unusually tight flight path restrictions at many of the nation's airport's: These are likely to dominate renewed discussions of air safety sparked by the recent airliner mishap in Washington, D.C.
Airports are opened and closed according to runway and visibility conditions. The visibility distance required for takeoff is traditionally minimal. But most pilots and aviation safety experts agree that, given the technical and ground assistance available, the limit is as generous as it really needs to be.
Ultimately it is the pilot's decision in bad weather as to whether the plane takes off or waits -- though the now decertified Professional Air Traffic Controllers Organization has long pushed for a transfer of that authority to ground controllers.
Generally, thunderstorms are viewed as posing a greater threat to safe flying than snowstorms. In any case, many pilots, who traditionally stress that they have the most to lose in any crash, readily admit that there are often strong pressures to take off when weather conditions are not the best.
''First, there are all those people sitting behind you who want to get where they're going,'' says one pilot. Second, if takeoffs on the runway have been proceeding normally, there is what one pilot describes as all around, general pressure to go.
''It's a subtle kind of pressure,'' says Chicago DC-10 pilot Vince Swinney, who estimates that he has canceled about three flights for weather reasons -- including one at National when it was surrounded by thunderstorms -- during the last 18 years.
Apart from weather in the air, ice conditions on the runway and on the plane itself -- particularly on the wings -- can pose considerable problems. Ice buildups slow the plane's ground speed and change its takeoff angle. The National Transportation Safety Board (NTSB) will be looking particularly hard at the effectiveness of the de-icing fluid hosed over the Air Florida jet before takeoff.
Chuck Miller, former director of the NTSB Bureau of Aviation Safety and now an independent aviation consultant, stresses that it is not the extra weight of the ice as much as the change ice makes in the shape of the wing. The changed shape affects the direction of the air flow over the wing, which makes takeoff more difficult. He says there may also have been icing on the tail of the jet, which would affect the pilot's ability to control his plane.
''Everything seems to suggest that there was some type of aerodynamic problem -- that the plane couldn't fly and couldn't climb,'' speculates Mr. Miller.
''The subtlety about icing is the (pilot's) inability to know you're in trouble until it's too late,'' he says. ''Your choice at a place like National is to go into the water or try to struggle the plane into the air.''
One critical need in the view of most pilots and aviation safety experts is enough extra runway length or vacant field space so that if a flight is aborted at the last minute, the plane has a place to go where prospects for survival are reasonably good. The Air Line Pilots Association (ALPA) has long campaigned for a concrete overrun of several hundred feet in both directions at National.
Miller, who does not consider such a runway extension practical at National, suggests instead that the airport's traffic be limited to smaller, lighter, local flights.