If you throw an object while the roc is carrying you, it does not fall to the ground

>LOOK
Midair, in the roc's talons
You are in midair. Fortunately a very large bird is carrying you, otherwise you
would fall. You are above a trackless wilderness to the east of a range of
jagged mountains.

The roc gains height and heads west towards the distant Flathead Mountains.

>DROP KNIFE
The knife falls, dwindling below you, never to be seen again.

The roc continues to fly west towards the mountains.

>THROW BURIN AT ME
You miss. (Mages aren't given a lot of training in this sort of thing.)

You are rapidly approaching a rocky eyrie containing an enormous nest.

>LOOK
Midair, in the roc's talons
You are in midair. Fortunately a very large bird is carrying you, otherwise you
would fall. You are dizzyingly high above a trackless wilderness to the east of
a range of jagged mountains.
The roc is holding:
  a magic burin

Shouldn't the thrown object have fallen to the ground here as well? It won't because ROC-F only handles DROP:

           (<EQUAL? .RARG ,M-BEG>
        <COND (<VERB? DROP> <DROP-IN-AIR>)

the-infocom-files / spellbreaker

If you throw an object while the roc is carrying you, it does not fall to the ground #20