When I perform a go around, how it is guaranteed there will be no traffic on my go around route for both controlled or uncontrolled airport?
At a controlled airport, the tower will route you or other aircraft as needed for seperation. If IFR, you will have a clearance to follow if you have to go around, either from ATC for that area, or as published, and once following the clearance you will go back to ATC for further information. At a non-controlled airport and IFR, the same will apply. If you land, you call and cancel the clearance, if airborne and you are talking to ATC and have visual to land, you may be able to cancel while airborne.
VFR is similar - either tower will direct you as needed, or you see and avoid when non-towered. If you use flight following, you will be talking to ATC until you get near the airport, they will often advise you of any nearby traffic before cutting you loose for your own approach and landing, with their last direction being something like "Nxxxx, airport is at your 12:00 and 8 mile, you have traffic at 1:00 and 5 miles, squawk 1200, frequency change approved."
[...] how it is guaranteed there will be no traffic on my go around route [...]?
Nothing is guaranteed, ATC will do its best (at controlled fields) to make sure that the spacing is such that going around will not make you run into traffic at least for as long as it takes for the tower to notice you are going around, and then issue instructions on how to enter the pattern again. But the final responsibility lies with you to see and avoid, even at controlled fields.
At untowered fields, it is your responsibility to rejoin the pattern in a safe manner. Usually this means not doing anything unexpected, like turning directly into the downwind or popping up into the pattern from below. It is your responsibility to "see and avoid". You may not be aware of all the traffic around untowered fields, even if you did get a traffic report on the way in. There are aircraft out there that are (legally) operating without transponders and even radios. The best tool a pilot has to avoid MAC (mid-air collision) accidents around an airport is your eyes. The second best tool is the adherence to procedures. Third are your ears, listen to position reports and build a mental picture of the airspace.
For IFR plans, this means following your missed approach procedures if you haven't already cancelled (or going up again and picking a new clearance). If you've already cancelled then you are VFR and VFR procedures would be followed.
The way I do go-arounds is:
- Initiate the go-around procedure according to the POH
- When positive rate/control is established, notify tower/CTAF
- Side-step the runway to the opposite of the downwind side to increase visibility
- Enter cross-wind 300 feet below pattern altitude if clear, or follow ATC instructions
At untowered fields some of the biggest things you need to watch out for are:
- Aircraft in the pattern that are not reporting position
- Aircraft entering the pattern unconventionally (extended downwind, extended final, etc)
- Aircraft back-taxiing