In my experience, CX crews are much less friendly and lenient towards cockpit visits on the ground due to (supposedly) company regulations. Back in the days when I wanted to be a pilot (not that long ago, I'm pretty young), I would rejected by the flight crew about 60% of the time even though I sent in a request along with a survey about the flight info. It would often come back with very vague responses and more likely than not a no for the cockpit visit after landing(again, blamed on company regulation).

I did similar things with AA & QF crews, they were all very friendly and willing to chat about their flying experience. I even managed to get a few loading information and flight plans from them. During the visit, some crews also allowed me to sit in their seat and move the controls. Definitely not the case with CX/KA, that never happened

It's likely the crew would make up excuses to not let you into the cockpit after landing as they don't want to extend their time on the aircraft any longer than possible. Just like everyone else who has just finished work, they want to get home as soon as possible.

Maybe the times people were allowed in after landing, it was a turnaround flight and the crew would be staying on board for a while anyway?

YMMV, IME, I've encountered crews that were extremely friendly and patient and willing to chat with you, verses others that would tell you to go in, take a look, come out

Its not allowed according to HK CAD, however, many of the pilots are happy to overlook that as they love their job, and enjoy showing it to others.

you will almost certainly get a no during flight. AFTER landing they MAY let you have a quick peak but i think its a no. if you are Media you can pre-arrange with their PR department but still wont get mid flight visit.

i miss the old day where u can sit in cockpit for the famous Kai Tak landing.. just like smoking was allowed in hospital in 60s visit to cockpit was ok in 90s pre 911

you are not permitted to visit while the flight is underway, if so that's quite a serious breach of company policy. The only people permitted up there are pilots and CX staff on or off duty, and ID staff family members only (regular ID nominees aren't permitted).

I'm not aware what is policy, but I can confirm I've been present in the cockpit during pre-flight proceeeings prior to pushback. However, I didn't ask...it is a story not possible for a public forum, but I was invited up for 15-20 minutes and left for good before push back. I was invited to visit again at the end but declined as I wanted to go home (our destination was HKG). So "it's possible" but I don't know what is the rule, except to say definitely no during movement. I think if you're really into airplanes and communicate that as much during the flight, you'd have a chance to visit after the flight is done.

If you read the travel blogs, many of those guys end up with photos in other airline cockpits with the plane on the ground. So it's definitely possible in the industry at least.

Normally you can visit on arrival. I have been invited a couple of times by the Captain.

I asked on a recent EK A380 flight and had to wait around until they'd finished the paperwork in DXB before I could pop in and say hello to the crew. I was only able to stay and chat for 5-10 mins but the flight crew were incredibly generous with their time and answers. as others have said, bit different to the 90's, which I was able to sit in the jump seat of a QF 747 on a SIN-LHR leg. I might ask on my upcoming CX MEL-HKG, as I have long layover.

I haven't travelled on EZY til last month.

Once a tarmac delay was announced, the first thing all the parents and kids on the plane did (I don't know was an invitation announced on the PA, I don't speak French and it wasn't in the English announcement) was to line up and have their photo taken in the cockpit.

I've never seen that on any CX/KA flight, even though I have view of the cockpit door for a good many tarmac delays.

I did see two jumpseat pax on my last flight. But the flight was packed to the gills and I assumed they found two staff/family who're adequately briefed and qualified to take the seats.

Cathay permits jumpseat passengers. In addition to pilots and FAs, a restricted group of additional ID status holders (immediate family and spouses of CX staff I believe) may fly jumpseat. ID ticket nominees NOT in that immediately family cohort aren't permitted, and if the flight is full they are simply S.O.L. And obviously, "no" to everybody else.

I have read about this on the BA forum as well. Maybe it's a European thing?

Passengers were allowed to enter cockpit with captain's discretion to visit years ago. However, after 9/11 and series of crime and terrorist attacks, company policy stated that no one except operating crew allowed to go in. The regulation also stated that there must be at least crew members in the cockpit at all time. Nowadays, passengers mostly just pass the flight log to cockpit to sign. One exception I saw was one captain allowed a passenger with disabilities to visit the cockpit on ground during layover time right after disembarkation.

I find it to be the case on most airlines (through observation) that passengers may be allowed into the cockpit after disembarkation at the discretion of the captain, though not Singapore Airlines.

Though that said, the only experience I have visiting a cockpit was after a Fiji Airways flight during disembarkation, after the (friendly) captain's approval.

I'd ask one of the cabin crew members (some time) after the first meal service finishes, when they are less busy. Ask politely if they could pass it on to cockpit for approval. Remember it's not an entitlement and be thankful even if rejected. Optionally, you may write a little sheet with "I would like to visit ... because (enthusiastic in aviation/a350/etc)" in a positive tone for the crew to pass to cockpit.

For enthusiasts a log sheet may be passed for the pilots to fill in as well, and chances are if they do not allow you in they might still help you with the sheet; don't bother if you don't know what it is.

As others suggested you are likely allowed in only when passengers disembark. I'll also suggest you try to learn a bit about cockpit environment so that you'll be less confused when the pilots introduce the cockpit to you. You may ask if photos allowed in the cockpit when you are there, but it's at discretion too and follow the crews' instructions at all times.