In AWS, There are aircraft types that are deemed not common to each other just because of speed difference, or difference in other parameters:
- DC4/6/7
- Dash 8 Q400 vs earlier models
- Earlier 737 models
- 757/767
- Fokker F-28/F-100
- Saab 340/2000
And there are also aircrafts that are forced to unify their speed because they are in same family despite their actual speed are different
- CRJ
- Dornier 328JET
- ATR
- Some other 1950s aircraft families lilke Convair
It is previously said that the speed have to remain the same in the same family because of the way route scheduling work, but would it be possible for commonality group to cross beyond families? As such, each aircraft group can have its own speed, and then they would remain common with each other just like how different engines within same engine family can be common with each other. And this can prevented a lot of issues that could be deemed inaccurate.