How to make up on prayers after a 16.5hr flight?

Wa alykum assalaam wa rahmatullahi wa barakatuh, Long flights across time zones can be confusing. Prayer times are based on your location and the movement of the sun, not origin or destination. Since you prayed Fajr before departing and landed in Los Angeles around 2:00 p.m., you are very cool and pray Dhuhr obviously. You came through east across Pacific then you missed 5 prayers and make all of time up. For future flights, check the approximate prayer times along your route. As a traveller, you may combine Zuhr with Asr and Maghrib with Isha’, and shorten the four-rakʿah prayers to two. If you cannot stand or face the qiblah, pray in your seat according to your ability. Allah says: “Be mindful of Allah to the best of your ability.” — Qur’an 64:16 Do your best, try not to miss anything intentionally, make up anything missed unintentionally, and ask Allah’s forgiveness. There is no sin for genuinely losing track of time, Insha'Allah, but once you remember, the prayer should be performed right. And Allah knows best.