The "No Oral Modification" Conundrum and its implications to aircraft leasing and beyond

A "no oral modification" clause (NOM clause) is as commonly found in a commercial aircraft lease agreement as in many other formal commercial agreements. As in the case that we will discuss below, it typically says that the "provisions of this Agreement shall not be varied otherwise than by an instrument in writing executed by or on behalf of [the parties]", and that "a right may be waived under this Agreement by an express waiver or variation in writing… and no act or course of conduct or negotiation on the part of such party or on its behalf shall in any way preclude it from exercising any such right or constitute a suspension or any variation of any such right." A recent New York court judgement brought to fore the question of whether an NOM clause effectively restricts the way in which the parties may consensually vary the contract. That question is not only interesting but is of much practical relevance as many airlines sought, and indeed may still be seeking, forbearance from their aircraft lessors during COVID-19 and its aftermath.