A plane is not a car
It’s tempting to think that you can jump in a plane, start the prop, and go anywhere with any number of passengers on board, within the limits of the number of seats available.

Performance varies from day to day, because of wind, temperature, runway status, and so on. All pilots learn that during the theory training for pirvate pilot licence. I won’t give a theory class here.

We all stop doing the performance calculation when operating uncer normal circumstances. If you take-off from your homebase, with your most flown plane, alone on board, you can probably skip the performance study. Nevertheless, you should have your performance table availble when operating outside your usual domain.

Typically, when the warm summer days come (30°C or plus), or if crosswind is strong, or if you have 3 PAX on board whereas you’re most used to one, or zero.

If performance is less than usual because of these factors, it is your responsibility as pilot in command to detect it when studying take-off and landing performance. If you don’t identify the problem at this stage, you could encounter an aborted take-off, which could be not so easy if runway is short. However, you can be sure that your passengers will remember it for long.

Plane performance is not pilot performance
The performance figures found in the books are sometimes unrealistic in the sense that they come from test made with perfectly new aircrafts, flown by experienced test pilots in optimum conditions.

The pilot influence is by far not negligible. Give the same plane to two pilots, they won’t get the same performance out of it. As an example, the take-off distance depends on how quickly after rotation is the speed set to Vx. Let the plane get a bit quicker than Vx during initial climb, and the take-off distance will increase.

The same applies for demonstrated crosswind. Most light aircrafts flying manuals do mention a demonstrated crosswind landing of 17 knots. This is not a formal limitation, but personally I will not try such a landing, except may be on a very long and 50 meters wide runway.

Another factor with a strong influence on performance is how the pilot is feeling… Try to fly once when tired, preferably with an instructor. You will be surprised how bad your technique could become.

At some stage, this can be compensated for by experience, but it is quite hard to evaluate your own experience. A poll in France shown that 85% of the interrogated private pilots do consider themselve as better than average pilots! Hardly true, isnt’it ? Nothing against french pilots here, I’m sure results would be equivalent anywhere.

Legal does not mean easy, nor feasible
It is legal to fly through a mountainous area in Echo airspace with a visibility of 1500 meters, or equivalent to 3o seconds of flight, as long as remaining clear of clouds. Doing so at 500ft above ground level is legal, if the area is not densly populated.

Can you imagine a high performance single (let’s say a Bonanza), flying in 1500 meters visibility, 500 ft above ground in an alpine valley, zig-zaging to avoid clouds, at 170 knots ? Legal. That would be really stupid, and infinetly risky, but legal.

Don’t expect any legal minimum to be enough for any pilot to be able to fly anywhere.

Have your own minimums
If you don’t know your personal minimums for the time being, take time to define them next time you cancel a flight, and have time to spend.

It is not possible to establish GO / NO-GO criterions, because this will vary depending on the type of operation. What I suggest is to have some criterions to define when it is worth to do a deeper than superficial analysis of flying conditions.

My personal list includes specific figures, but also some environmental clues:
1) Any wind above 10 kts
2) Any visibility below 10km
3) Any ceiling below 1500 ft
4) Any temperature above 25°C
5) Clouds moving visibly
6) Birds hovering in wind

Any of this thing would lead me to a deeper analysis of the conditions before starting a flight. Establish your own list, and make it evolve with new experience, and you will simplify your decision making process by having strong basis.