New York Codes, Rules and Regulations
Title 21 - Miscellaneous
Chapter XXIV - The Port Authority Of New York And New Jersey
Subchapter D - Air Terminals
Article 1 - John F. Kennedy International, La Guardia and Newark Airports
Part 1261 - Aircraft Operations
Landing and Taking Off
Section 1261.22 - Landing of aircraft without two-way radio restricted

No aircraft may land or take-off at an air terminal without prior permission unless it is equipped with a functioning radio capable of direct two-way communication with the control tower, except in case of emergency. In addition, no aircraft may land or take-off at La Guardia Airport unless it is equipped with a functioning radio capable of direct two-way communication on the VHF frequency designated as ground control, except in the case of an emergency.