How many letters does the top answer for “transport by boat or aircraft” have?

The most common answer is ferry (5 letters).

Crossword clue: transport by boat or aircraft

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

ferry 5 letters wn-def

transport from one place to another

ferrying 8 letters wn-def

transport by boat or aircraft

transport in a flatbottom boat 50% similar → lighter