I am very familiar with the letter.

The single most important point of the letter, which was obviously not as clear as intended, was that by combining Profit Sharing with the normal pay unintended consequences are brought into play regarding the normal pay portion of the check.

If a pilot were to defer 100%, all the profit sharing would go in. The taxes due for the profit sharing (FICA and small FED and State) could wipe out the entire "normal Pay" portion of the paycheck.

If that happens, there might not be enough left over for pesky things like mortgage payments and other automatic deductions.