I was a passenger on a commercial aircraft on final approach into Salt Lake City. As we desended to approximately 1000' the pilot suddenly gunned the engine, climbed and aborted the landing. He then explained that the landing was aborted as there was another aircraft on our runway.
Is this a reportable incident to the FAA?
It depends.
There are two general situations. One where the other aircraft was supposed to be on the runway and one where it was not.
In order to increase traffic density and keep the system working, aircraft do not wait for the aircraft landing in front of them to clear the runway or, in single runway fields, for the aircraft taking off in front of them to get airborne. The separation distances and times are such that normally, the other aircraft will clear the runway but sometimes it doesn't work out. A departing aircraft might have been given a clearance to take-off but doesn't respond quickly enough, or a landing aircraft might have a problem causing the pilot to stop on the runway to check it out or perhaps simply missing the turn-off they were supposed to take.
ATC might see this happening before the landing aircraft does and issue an instruction to "go around" or, the pilot might have seen that the runway was not clear and made the decision to do so.
This happens around the world dozens of times a day and is not reportable. The system worked as designed and safety was not compromised. It is most likely to be what happened in your case.
The other situation is where the other aircraft should not have been on the runway, called a "runway incursion". It might have been instructed to "hold short" of the runway but then entered it or might have mistaken the runway for a taxiway.
This is reportable. The captain has the authority and the duty to ensure that the runway is, or will be clear when they land and to abort the landing if not. If the captain cannot be sure, they are required to go around rather than press on in the hope that it will be clear. Again, the system worked but safety margins were compromised and thus, the incident is reportable, both by ATC and the landing captain. If it was a runway incursion, the crew causing it, assuming that they realise that they made a mistake, are also required to report it.
Although I've mentioned aircraft, there are many things that might not be authorised to be on the runway such as people, ground vehicles, animals, construction equipment etc. Occasionally, pilots are attempting to land on the wrong runway, perhaps one closed for maintenance, and will go around when they see stuff on it. These are all reportable.
No, from your description this occurrence is probably not considered an incident, and probably would not require reporting to the FAA or NTSB.
A go-around, or aborted landing, is not inherently an incident, but is a relatively common procedure as the other answers have aptly explained. While the circumstances surrounding this go-around could possibly be classified as an incident (depending on what those unknown facts are), from your description this is unlikely.
The other answers are good, but I want to offer the FAA and NTSB definitions and regulations surrounding such an event.
Under FAA jurisdiction, the term incident is defined in 49 CFR 830.2:
Incident means an occurrence other than an accident, associated with the operation of an aircraft, which affects or could affect the safety of operations.
49 CFR 830.5 further defines various serious incidents which require providing immediate notification of the serious incident to the NTSB. The definition of a serious incident includes the following:
(12) Any event in which an operator, when operating an airplane as an air carrier at a public-use airport on land:
(ii) Experiences a runway incursion that requires the operator or the crew of another aircraft or vehicle to take immediate corrective action to avoid a collision.
Given the above, your event would require notification to the NTSB if both the following were true:
The first case is unlikely, but possible. This go-around could have been in response to an incursion, but most likely the aircraft on the runway was authorized to be there.2
The second case is less likely, especially given your description. In my estimation as a pilot for an air carrier, a go-around at 1000 feet above the runway does not constitute immediate corrective action. Those involved that day might have seen it differently. Note that at typical approach speeds it would take at least 1-1.5 minutes on the approach from 1000 feet above the runway to the point that the aircraft crossed the runway threshold. If we were to assume this event involved a runway incursion, the FAA would likely categorize this as a Cat C event3 (or possibly Cat B), which would be a relatively low severity event.
Moreover, even if the event did qualify as an incident, much less a serious incident, a report is only to be filed by specific request of the NTSB (see §830.15 below). In other words, even if the event was a serious incident requiring immediate notification to the NTSB, a report would only be filed at the NTSB's request.
See 49 CFR 830.15:
A report on an incident for which immediate notification is required by §830.5(a) shall be filed only as requested by an authorized representative of the Board.
1 The FAA defines a runway incursion as:
Any occurrence at an aerodrome involving the incorrect presence of an aircraft, vehicle or person on the protected area of a surface designated for the landing and take off of aircraft.
2 According to the FAA:
Approximately three runway incursions occur each day at towered airports within the United States.
From Runway Incursion Avoidance p. 2
Three incursions per day is significant, but given the daily number of aircraft and vehicle operations at towered airports within the United States, incursions are comparatively rare.
3 The FAA categorizes incursion incidents into four categories, ranging in severity from low to high, with Cat D being low, and Cat A being high severity. The highest severity level would be an accident. Only Cat A is considered to be a "serious incident" requiring notification to the NTSB. For more information see the FAA's Runway Safety page including the following definitions of Cat C and B incursion events:
Category C is an incident characterized by ample time and/or distance to avoid a collision.
Category B is an incident in which separation decreases and there is a significant potential for collision, which may result in a time critical corrective/evasive response to avoid a collision.
