the ds ii was far smaller than an earth-sized planet, which star destroyers are parked above on a regular basis, and would thus have a much weaker gravity well. there is no reason for the engines/repulsorlifts to immediately fail and send the ship plunging into the equivalent of a moon's well, upon losing contact with the main bridge. as i said, imperial ships routinely orbit planets - hell, they're constructed in orbital shipyards -, and it's hilariously inept not to have an autopilot that would maintain orbit if something were to happen to the bridge
Well, for one thing, DS2 likely:
1. Has a higher density than the average planet (you know, from all that armor plating and that giant hypermatter reactor).
2. DS2, being 900 km in diameter, is about 1/7th the diameter of Earth. Not an inconsiderable size and gravity.
3. Gravity has a bigger effect on higher-mass objects you dolt. While a standard ISD might not have plunged to it's doom within the DS2's gravity well, the Executor is a much higher mass warship, being several times longer and much higher volume (and thus density and mass). The Executor would be more prone to such a failure than an ISD.
4. Perhaps they don't use autopilot controls because of heavy jamming and ECM usage (which is canon), and instead use actual helmsman officers. It's not like a Trek ship has an autopilot failsafe. The helmsman buys the farm, the Enterprise is just as screwed as the Executor.
how so? the senior officers would all be on the primary bridge.
No, they wouldn't. If you had any sense, you'd realize this. Most of the senior officers are almost certainly on the primary bridge, but some of them would logically be on the secondary bridge, in the off-chance that the primary get's shot to pieces. It's called "not putting all your eggs in one basket". Further, senior officers are not automatically more skilled officers. They have experience and time-in-rank, but neither of those equates to skill.
A junior officer could very well be completely capable of competently taking command of a warship, whilst a senior officer is only in the position of command by virtue of political connections (which is precedented in the SW universe).
The Executor lost control because George Lucas thought it would be awesome to have it crash into the Death Star with a big explosion. Any technical/canon reasons are made later. Which is why I personally find it amusing these fairly trivial details are important to you, but each man to his own.
Well, that's almost certainly true. But you can't use authorial intent/fiat in versus debating, it's not objective. This is because the objective way to conduct a versus debate is to analyze each 'verses media as if they were documentary or biographical accounts. Analyzing in that manner allows no room for authorial intent, so we have to come up with a likely reason that the Executor lost control and crashed into DS2, and the most logical, reasonable, and likely explanation is that Executor was trapped by the gravity well of DS2 and thus crashed into it.