FPL报里的DOF，Date of Flight，代表航班预计要执行的日期。在发送后续DLA报文时，要附带上原先的DOF。我一直有个疑惑，如果7月1日23点的航班，延误到7月2日怎么办？DOF怎么写？

上个星期，我在一个叫《FAA ICAO Flight Planning Interface Reference Guide》的文件里找到答案：

Note:If a flight plan was filed with a valid DOF/, then a change to the departure time that also changes the date of flight (i.e. delays past midnight) should not be communicated using the DLA message.a CHG message should be used to convey the Field 13 and Field 18 changes using Field 22. Remember that the Field 18 filed in CHG and DLA should always reflect the DOF/ that was previously filed.

所以，如果航班延误超过午夜，需要发一个CHG报，把DOF也改成后面一天，不是发DLA。