it's bad to pop first IF the enemy team has uber because then they have ad if you pop

https://d3eum8lucccgeh.cloudfront.net/designs/58769/detail_PopIt.jpg

if your pocket (or the person you're healing who is engaging in combat) is able to easily be one-shot, you should probably pop. Typically over 100 health is safe but under that more and more things start to be able to kill your heal target.

If you also see a lot of people turning to shoot at your heal target, it's probably best just to pop to negate the damage your heal target would have taken if you didn't pop. That might result in a bad uber but depending on the situation it's probably better than dropping whoever you're healing.

if you pop and the enemy is so far away that popping would result in nothing or you already have other huge ads like player ad, dropping wouldnt make the situation much worse, so you can call that youre milking and live (or die) with the result.

From what I understand if you are bombed by a soldier you end up in a few different situations. If you take a direct rocket then you'll most likely be forced. If you surf a splash rocket far away and don't crater then you can probably hold onto your uber. If you surf a rocket but take crater damage you probably will have to pop.

Im pretty sure that a good medic will be in a position to leave or surf so that they can hold onto their uber and give their team a chance to keep them alive or get them out.

Please correct me if Im wrong, I like playing medic sometimes.

count his rockets and know how much damage each rocket is going to do
use it if youre going to die

also if the guy youre healing ever says to pop, dont milk just use

Communication is a big deal for the contexts you are talking about. Aside from what pelt said about your pocket or someone else saying to pop it and therefore needing to listen to that call, you can't just hope that your team kills something without calling it yourself. You need to communicate, especially during messy transitions or situations that can quickly become unideal. One of the easiest things to be as medic is to be aware.

Also, keep in mind that the particular context you mentioned has a lot to do with specific teams. Some teams benefit from their medic popping early or "just-to-be-safe" during a transition. This is in order to get buffs to better deal with the uber disadvantage (usually) they face at that point and typically the medic plays pretty safe at that point while making sure certain players have fresh buffs at all times. Other teams benefit from their medic milking hard and gaining a lot from it (i.e. two people sacking into your team uselessly), even if their medic might end up having to drop. There's the bizarre case of a team's medic dropping uber and then the same team wiping the enemy team as well (I noticed this a lot when I played on -bird noises- with different medics across various seasons). Not a very logical scenario though and more a case of a team getting excited because of dropping the enemy medic and not taking time to push with their own heals.

By the way, not really related to the question at hand directly, but this thread made me think of the various bits of timeless advice Platinum gave on TF.TV a couple years ago. Some direct links:

Regarding calling
Pocket-team relationship
#42 Pocket-medic chemistry
#58 Pocket-medic chemistry

Don't ever pop uber. You don't need uber to win in tf2, despite what the so-called "pros" in this game have led you to believe.

Every time you drop, just think of how your movement and positioning could be better.

Ditto for your team, if they ever complain about being not ubered, you should just let them know (polite but firm) that their positioning and game sense is out of whack and they need to get on the same page as you.

Basically, you don't need uber if your team is able to focus fire well enough. Also, you can counter the enemy's uber with good focus fire. They can only have one ubered player at a time after all so if you're team is able to focus the non-ubered players down you can just make it into a 2vs6 once their uber runs out.

Definitely do try this in pugs, it will help take your game to the next level.

depends on the situation rwally. If you're pushing into last from second with 20 minutes left at a draw or win on the rounds don't be afraid of dropping but in other situations where you're short on time staying alive should be a priority.
iirc mirelin had a great thread on etf2l on wen to pop or risk dropping

Can someone link this Pls.

http://etf2l.org/forum/tactics/topic-31495/page-1/

If there's a very real chance that the next shot the enemy will potentially hit on you will make you drop, then just pop it. Popping is better in every way in comparison to being dead, because you'll 1) be alive 2) be ahead on uber by about 25-40% instead of watching the death cam, and 3) you'll be able to keep your teammates healthy in the meantime. If you didn't pop and you lived, yeah that's cool, but you put your team in a horrible position if you drop. If you use, you'll probably lose a control point and then you should sustain at a stalemate.

If you're down by one round and you really need to pull out a solid push with not much time left on the clock, then yeah, I'd do everything you can to hold on to the uber.

A decent amount of the time, you can get around even being in this situation by making sure your team is aware of their surroundings. They need to check for hiding enemies, as well as turning around and helping you out when you're being pressured. Obviously, it doesn't totally rest on your team's shoulders, as you need to make sure your positioning is solid as well.