The September 2001 column, "When is it an Emergency?" reviewed how a pilot can recognize a situation where the exercise of his emergency authority may be necessary. In particular, you may recognize "an emergency" as a condition that occurs during flight that causes you to be reasonably concerned about the safe outcome of the flight. Practically speaking, you will most assuredly know that you are experiencing "an emergency" when it is happening.
So, we know that a pilot facing an emergency situation is going to do whatever he or she deems necessary under the circumstances, based on practice, skill, experience, and judgment, to survive the predicament that has arisen. This may include declaring an emergency, deviating from a flight rule, and/or being given priority by air traffic control. But, what must you do afterwards? In any of these events, you may be required to send a report of your emergency to the FAA.
There are two regulations that apply in this regard, and each may require that a pilot who has experienced an in-flight emergency submit a written report of the emergency to the FAA. However, both regulations specifically state that the report will only be required if the FAA requests such a report. It is not an automatic responsibility. And, it is not designated that the report be made on a particular form; rather, it may take the form of a statement that you type or handwrite onto a piece of paper. But, before we get into these details, let's look at the exact language of the regulations.
FAR 91.3(c) states, "Each pilot in command who deviates from a rule under paragraph (b) of this section shall, upon the request of the Administrator, send a written report of that deviation to the Administrator."
FAR 91.123(d) states, "Each pilot in command who (though not deviating from a rule of this subpart) is given priority by ATC in an emergency, shall submit a detailed report of that emergency within 48 hours to the manager of that ATC facility, if requested by ATC."
As you can see, there are only two circumstances under which the FAA may require that you send them a report. Otherwise, the FAA may not have authority to require you, by regulation, to send them any of this information. And, if the FAA does request that you submit a written report, the FAA will tell you what information is required and to whom it should be sent. I recommend to pilots submitting such a report that they prepare it so that it is simply and factually written and that any speculation or conjecture is avoided.
If the emergency is related to an accident, then you may have other notification and report responsibilities. However, these other reporting responsibilities are to the National Transportation Safety Board (NTSB), not the FAA. It is important to recognize this distinction, because too often, events are unnecessarily reported to the FAA when they may only need to be reported to the NTSB - and some things get reported that didn't need to be reported at all because they did not fall within the definition of an accident, which is set out in the NTSB's regulations.
For your own protection, knowing what your regulatory responsibilities are in making reports to the FAA or to the NTSB is important. This is an area where seeking competent legal advice is to your benefit. The first step is knowing that the rules are there and that there are distinctions and differences that may be meaningful to you.