EK381 on Friday is not sold out either. Why do you think it is "fully booked"?
Results from ExpertFlyer.com
Code:
Flight Availability Search
Departing HKG on 22/07/16 12:00 AM for DXB
Flying EK
Frequency
Flight Stops Depart Arrive Aircraft Reliability Available Classes
0 Connections
EK 381 0 HKG DXB 388 Daily F4 A4 J6 C6 I6 O0 P0 Y9 E9 R9 W9 M9 B9 U9 K0 H0 Q0 L0 T0 V0 X0
I reckon that's probably over in y