But IS any kind of guarantee offered by commercial airnav data suppliers like Jeppesen? Are there any stories known of people getting compensation for errors due to incorrect commercial data?
Not as such but if you flew with say Jepps and did a bust, you can say to the CAA "look here is my chart, it is current" and if there was actually a mistake on it (which is hardly unknown with Jepp ones) they would find it very hard to prosecute.
There is almost no insurance angle here because flying with hopeless charts is negligence, and insurance covers negligence.
There is no law (USA or UK) which stipulates a particular chart must be carried or used. It comes down to due diligence by the pilot.
I would guess Jepp have product liability insurance so if one of their approach plates is wrong and somebody gets killed, they are insured. I vaguely recall this has happened somewhere but it must be extremely rare.
But there is almost zero risk of anybody claiming over a mistake on a
VFR chart or a "VFR" flight planning program because VFR=VMC and only a d1ck will fly into a hill in VMC
IMHO, IANAL, if you sell a "VFR" flight planning product then provided you make sure the mapping data supplied is obviously too poor to use alone (e.g. Navbox) there is no chance of ever getting successfully sued.