One stated goal is to handle more passengers by accommodating more large planes. The problem with this reasoning is that large planes are not generally economical to operate when not filled or on short flights. When larger aircraft such as the DC-10 and MD-11 and the L-1011 flew out of LaGuardia, they could not operate even close to their maximum weight due to inadequate runway length and difficult departure and approach patterns.
Additionally, LaGuardia has in place, with a handful of exceptions, a 1,500-mile perimeter rule, which means that no aircraft may depart on a nonstop flight of longer than 1,500 miles. Airlines make less money when they are forced to operate aircraft with unused passenger and cargo capacity, over distances shorter than their ideal ranges.
LaGuardia's proximity to Manhattan is desirable for tourists and business passengers. However, I don't see any mention of a rail link, something that's already in place at both Kennedy and Newark airports. That means that increased passenger capacity at LaGuardia, if used, would be accompanied by increased roadway traffic.
LaGuardia's location within New York City means that takeoff and approach patterns fly over some of the most densely populated areas in the nation. While air travel today is safer than virtually any other form of transportation, the two times during any flight that an aircraft is most vulnerable to catastrophic accidents are takeoffs and landings.
Instead, it may be time to consider downsizing LaGuardia to a regional commuter facility, with high-speed rail links from LaGuardia to Manhattan and from LaGuardia to Kennedy Airport. Also, add a new airport, perhaps in Rockland, and expand capacity at Long Island MacArthur in Islip, Westchester County Airport in White Plains and Stewart Airport in upstate New Windsor, as well as at Kennedy and Newark.
Leonard Cohen, Wantagh