Current airline doesn’t have any routes there, but how come when I tried with a past airline, my 733 from Calgary Was not getting full capacity? I also try a CRJ 700 and A320 from San Francisco And again I was getting shorted passengers. In real life the Santa Ana Airport KSNA, Can accommodate to a 757 And I know Alaska airlines uses the from B737-7 from PDX and SEA, And I know the flight from PDX are Always full. Virgin America Operates an A320 from San Francisco, Don’t know occupancy of their flights. Air Canada operates a A319 from Vancouver British Columbia. Southwest operates 737-7 to and from from Chicago Midway and Again Don’t know Their capacity either.
And how many people from those passengers go to that city only?
You have to understand that sometimes even over 90% of people traveling on a certain route are connecting passengers 
All I know is that a 737 should be able to handle a full load.
SNA has a rwy of 1700m. that limits the max payload quite a bit.
We’ve had this topic quite a few times.
Yes, there are airports which cannot be served in the game but can in real live.
BUT, there’s way more airports that can be served in the game (even at MLW/MTOW) while they cannot in real live - AS doesn’t cover the airports’/aircraft’s PCN/ACN for example.
Runway length isn’t everything.
yukawa and AK are right.
Please remind that in real world it is most unlikely that a civil jetliner is able to take a full payload (with maximum capacity) AND 100% fuel. There is almost always a compromise. For example the 737-300 was introduced in the mid-1980s by several US-companies to serve airports in California like SNA but such flights were payload-restricted to reach destination X. IIRC correctly BAe 146s were the least restricted jetliner in its class payload-wise because the length of the runway and the performance of the BAe 146 was fine enough and the aircraft was able to be quiet enough. At least AirCal was able to trade-in one loud 737-200-flight for two BAe 146-departures. I think that no 737-300 was/is able to lift with full payload from SNA to Calgary. It is similar to the Super 80-services once run by American Airlines. The performance was good enough to reach Dallas with a decent payload I think but destinations beyond that range were only possible with heavy payload-restrictions.
Regards
PS: I am not aware of other types but I have a manual from an airline with the interesting fact that an MD-87ER can take "nearly 100% payload" and 100% fuel at the same time: full fuel-tanks and 133 seats are possible, only six seats below the maximum allowed on an MD-87. For comparison: full fuel-tanks in an MD-83 are only possible with a reduction of the passenger-capacity from 172 to 155 which explains why several companies configured them with 155 seats to have that margin. However the length of the runway and air-pressure as well as air-temperature and other factors are also important.
SNA has a rwy of 1700m. that limits the max payload quite a bit.
Based on my current airline's experience at SNA, I am quite confident that this is the explanation to the original question posed in this thread. My outbound flights (with a 73G) are consistently booked at full capacity (passengers and cargo) while my inbound flights consistently carry 20 fewer economy passengers and zero cargo. My inbound flights always have 88 passengers in economy, which leads me to believe that this is the maximum allowed for inbound flights with the seating configuration I use. In this particular case, it appears that the short runway is the deciding factor here.
Outbound, I am carrying 108 economy, 20 business, and 3 cargo; inbound, 88 economy, 20 business, and zero cargo. Luckily, my inbound flights are still making a decent profit.
Wsxqaz, if you use the performance check tool for the type of aircraft you are using and compare the ratings in each direction, you will see the difference illustrated.
hehe, since Wsxqaz had about one year to ponder about that, I think he might have figured it out by now ;-)