Sometimes I think there is a disconnect in understanding distances in space, either on my part or on others' part. The 100D distance of an earth size world (slightly above average in Traveller) to the orbital starport is like 5-6 hours, which assumes they are braking for half the distance so as to arrive slow enough to dock. For a 6G patrol craft, it's two hours IF they need to slow down. Which they don't if they are zipping out to deal with a bogie. Assuming that they have to come all the way from the planet and aren't much closer already. And the whole place is going to in a pretty reasonable sensor net that will notice loitering ships unless they have state of the art milspec stealth (which is extremely expensive).
It is not a misunderstanding about distances (
Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is.). There seems to be a misunderstanding about what you need to do when you get there (which is a problem with the space combat rules only using G). The vessel you wish to inspect will have arrived at the 100D limit and would usually arrive stationary. After 1 hour at 1G it will be doing around 36 km/s. After 1 hour at 6G without slowing your interceptor will be travelling at 216 km/s . You don't get to shed that instantly. You will arrive at the intercept location (or rather the point you predicted the interception would be) with a relative velocity of 180 km/s and after a single space turn of 6 minutes you will have overshot by around 64,000 km even if you had cut thrust on arrival. Whilst it is possible that you could conduct the sensor collect in that time and decide a course of action, if you decided you did need to board to carry out a verification or engage you would need to turn around to slow down to a stop (which takes another hour) and then accelerate back the other way, then at some point you will need to turn around again so you can cancel the reversing and accelerate back up to a sensible speed to match that of the target (which might have changed course during all this messing around).
That is why you use the standard calculation* (or at worst modify to allow you to arrive at the same speed as the target). Of course when you set out, you didn't actually know what the vector of the target ship was as your sensors didn't have the range to determine that. SOPs would probably be to assume 1G in the direction of the centre of the planet but the pirate might choose to confound that by selecting a non integral thrust or a different vector.
Where is this magical sensor net coming from? To cover the average size 5 planet 100D you need hundreds of thousands of them if you want more than "there's something there...". If they are not at the few Lagrange points then they need to be able to reposition and you are talking a small ship (or drone), the cost is going to be several MCr each, plus maintenance... And how exactly does it identify a ship as a pirate if that ship isn't behaving piratey?
And that's assuming that there isn't a customs/patrol base at the L2 point, which is about 125D for Earth IIRC. Which seems kind of likely to me, considering we have the James Webb Telescope there with our extremely limited space flight capabilities.
If you put a patrol base there (which would be an Imperial base since 125D is Imperial space) and were able to require all traffic to jump into its vicinity for possible inspection you could eliminate a lot of legitimate traffic as suspects (assuming astrogation allows ships that level of control over your emergence point). If something jumped in on the other side of the planet though, it would be in a worse position than an intercept launched from the planet, but it would definitely be something to investigate. If a pirate decided to pretend to be legit however they would just use the designated arrival point like everyone else. Since they are not painted black with a skull and cross-bones motif they are just another routine check.
There are exceptions, of course. Regina is a gas giant moon, so the 100D range is rather larger than normal. And some worlds are well inside the 100D of their Sun. So those can be problematic with longer travel times.
Space piracy is fun and it seems like a thing you'd want to have happen. But that's an extremely limited amount of time for a pirate to ID a target ship, chase it down, force it to stop, steal its cargo (or the whole ship), then escape the 100D limit again and get away.
I tend to assume that many pirates have identified their targets and cargos at the spaceport (via proxy probably). They set out with a higher G vessel along a similar but not identical path a little later than the target to allay suspicion and plan their intercept to be about an hour or two before the target hits the 100D limit giving an hour to conduct operations. The clock only starts ticking when the target discovers he has a tail and that will be at his sensor range. With the limitations of civilian sensors and poor sensor operators legitimate contact with other vessels is likely to be at very long range as you can only avoid closing on a ship that you are aware of. I suspect there is a lot of "hey buddy mind backing off a bit" before suspicions are aroused so the mayday may not come immediately. If you only encounter a pirate every 4 years the vast majority of sensor bubble incursions are accidental or legit so there will be some delay in activating anti-piracy procedures. Assuming the Mayday is not jammed it will take seconds at most to get to someone who is in a position to help. If the emergency channel is jammed then that itself will alert the authorities something is up, but it will take time to triangulate where the jamming signal is originating. That gives you until the target reaches the 100D limit or an interceptor arrives to engage, loot (or tow the whole ship or put a prize crew on board) and push hard to where you can jump (and I would recommend pirates to have early jump so they can jump immediately operations have concluded). Clever pirates might deploy cry baby drones capable of transmitting false emergency or emergency channel jamming signals timed to fire up before the time of the intercept decoying the authorities away from the real issue. Really sneaky pirates might put such a drone in cargo they pay to have shipped by another trader with a transponder coded to match the carrier.
It is very difficult for a pirate to predict when they would emerge from jump so chasing ships from arrival isn't practical (not least because they probably want to be fully fuelled before they reveal their intentions). Of course if they are opportunistic they could just hope for the best. I suspect these pirates (probably Vargr) get caught a lot. Using a stealth ship would be a better proposition for this sort of attack but it is an expensive option probably reserved for military cutting out operations, but who is to say that "pirate" is freelance.
I don't feel like that 2-6 hour window is "the wilds of space". Maybe I'm wrong about that.
2-6 hours hours is plenty enough to attack a vessel and loot it. If I broke down 2-6 hours from the nearest town it would be a big deal to me, let alone in the cold vacuum of space. It is about as wild as the average spacer will experience as most do not do deep space exploration or even inter system travel. That is why belters are in the Drifter career - "Wild Men I tell you!".
Lets not underestimate this 100D. For an earth sized planet that is over a million km. Lets not toss that number off casually. A MILLION km. Realistic sensor range is less than 50,000 km, 5% of that. After that first hour at 1G you are pootling along in a tiny bubble of light at 36 km/s but getting faster all the time. The faster you go the less time you have to react and the more time you will need to turn around. You can see where you need to go, but not much else. You are relying on statistics to keep you safe.
Like taking a cross channel ferry chances of it going wrong are low and most people don't even consider it, but those life rings and boats are there for a reason (not that your trader is carrying a lifeboat). Everyone is happy in the bar, but every once in a while something does go wrong. An unprotected human in the UK North Sea in winter has a life expectancy less than an hour due to exposure (less if they panic as movement sheds body heat more efficiently). Even those who get into boats are probably going to be wet, and scared and possibly irrational. The fact that land is only a few hours away is cold comfort Outcomes are seldom universally good. But hey, the coastguard will be there in an hour, so that's all right...
Traveller needs more reasons to be travelling in real space over interplanetary distances, imho. You want players to have reasons to be beyond immediate help. So that they have to do the daring rescue, board the derelict ship, or escape the pirates instead of just calling the coast guard. And to do that you need space ships travelling to the asteroid belts or Jupiter, etc without just doing a safe micro jump.
Or you could just let them know that "immediate" help is going to take several hours to get there. People bleed to death in hours, fires spread beyond control in hours, air can run out in hours. Advising them they "just" need to survive 12 turns of space combat with a 400 ton "trader" that has just revealed itself as a corsair should be scary enough.
*Even missiles use the standard calculation presumably as it recognises that they probably need to course correct in the final few km.
