Business travellers with flights to Korea, China, Taiwan and Japan should check arrival and departure times with their airline following the eruption of Shinmoedake, a volcano on the southern Japanese island of Kyushu.
Closer to Shanghai, Taipei and Seoul than it is to Tokyo, the ash cloud from Shinmoedake has reportedly delayed flights in the region as airlines play it safe to avoid the volcano's plume.
Flights to Japanese airports are already affected by Friday's earthquake and tsunami, plus the following relief efforts. Most airlines are waiving change fees for flights to and from Japan for travellers who need to make different plans.
But a quick glance at the map shows that international airports in Beijing, Shanghai, Taipei, Seoul and Busan are near enough to be affected by Shinmoedake's ash plume.
The plume also lies right in the path of airline routes from Asia to North America, meaning flights from the US and Canada to hubs Hong Kong, Singapore, Bangkok and Kuala Lumpur are subject to delays -- and potential diversions if flying around the ash cloud means that aircraft have to stop and refuel en route.
Knock-on effects across airline networks if aircraft are out of position could also be felt, even for travellers on different routes.
European flights experienced days of disruption after the eruption of Icelandic volcano Eyjafjallajökull last year.
As ever in situations like this, contact your airline directly to check whether your flight will be leaving on time, and prepare before you leave home in case disaster strikes while you're on the road.
If you need to get to Japan urgently, consider alternate routes into the country after the earthquake/tsunami, and try to avoid Tokyo.
About John Walton
Aviation journalist and travel columnist John took his first long-haul flight when he was eight weeks old and hasn't looked back since. Well, except when facing rearwards in business class.