Is it necessary to have a letter of recommendation.

Not necessary.

Falcon, this is straight from management:

When you endorse a candidate, you are personally attesting to a candidate’s
skill, qualifications and suitability for employment with FedEx Express.
Should your candidate be hired, you will play a major role in the mentoring
of that individual from post IOE through the end of their probationary
period. You will not be able to offer endorsement to another candidate
during that period. Should your candidate not succeed, you are free to
provide another endorsement.

In order to get a letter of recommendation, the person must attest of your skills. Usually someone who has flown with you. Try to find someone with FedEx that has flown with you and go from there. Good luck.

Are the Kennedys gun-shy?