During the 1970s, travellers were strongly advised to reconfirm,[4] as cancellations actually happened,[4] even on domestic flights.[8] Since the 1990s, some guidebooks told that domestic flights do not need reconfirmation.[9] By 2000, there was a notion that reconfirmation became something of the past, and travellers who actually did reconfirm may have decreased.[10] However, as of 2021[update], it is still allowed to mandate reconfirmation, so the risk of being cancelled remains.[5]