You can take MetroNorth Railroad from New Haven to Grand Central Station, and from there you can take the subway to JFK.
See the second link for MetroNorth Railroad Schedules. You will need to click the icon on the right, where it says, "Click for lines EAST of Hudson - Harlem, Hudson, New Haven," to find train schedules from New Haven to Grand Central Station.
At Grand Central Station, you will need to take the S shuttle train (color code grey) west across 42nd Street, from Grand Central (East 42nd) to Times Square (West 42nd).
Then walk through the tunnel that connects the 42nd Street-Times Square Station to the 42nd Street-Port Authority Bus Terminal Station. At the 42nd Street-Port Authority Station, get the Brooklyn-bound (Downtown) A train (of the A-C-E, the blue line). Take the Downtown A train to the Howard Beach Station in Brooklyn.
At the Howard Beach Station, you can catch a shuttle (called the AirTrain) that drops you off inside the JFK terminals.
John F. Kennedy -- JFK is the airport code.
John F. Kennedy International airport - IATA code JFK, is the airport named after JFK.
John F. Kennedy International Airport was created in 1948.
The airport is called john F. Kennedy and its locate in Queens, New York.
John F. Kennedy International Airport (JFK) is the primary international airport serving New York City.
JFK Access RoadNew York, NY 10010-3672
John F. Kennedy International Airport (JFK) is the primary international airport serving New York City. New York International Airport opened in 1948. The airport was officially renamed John F. Kennedy International Airport (JFK) on December 24, 1963 in memory of John F. Kennedy, the 35th President of the United States, who was assassinated on November 22, 1963.
146 miles John F. Kennedy International Airport (JFK) to Albany International Airport (ALB)
New York International Airport opened in 1948. The airport was officially renamed John F. Kennedy International Airport (JFK) on December 24, 1963 in memory of John F. Kennedy, the 35th President of the United States, who was assassinated on November 22, 1963.
New York International Airport opened in 1948. The airport was officially renamed John F. Kennedy International Airport (JFK) on December 24, 1963 in memory of John F. Kennedy, the 35th President of the United States, who was assassinated on November 22, 1963.
The airport was renamed John F. Kennedy International Airport on December 24, 1963, one month after the assassination of President John F. Kennedy.
John F. Kennedy International Airport (JFK) is the primary international airport serving New York City. It is located in the New York City borough of Queens, 10 miles southeast of Midtown Manhattan. John F. Kennedy Memorial Airport is in Ashland, Wisconsin.