AIM 4−2−4. Aircraft Call Signs
When aware of similar/identical call signs, ATC specialists will take action to minimize errors by emphasizing certain numbers/letters, by repeating the entire call sign, by repeating the prefix, or by asking pilots to use a different call sign temporarily.
所以在空中是可以临时指定呼号的,以前一直记得可以的,现在找到出处了。
针对联程航班,如果把同一个航班号的航班分在两个飞机上,理论上可以出现在同一个区域,只要指定不同的呼号就行了。但这样的确给管制员增加了巨大的风险。