Once the interval exceeds 24 hours, Current Surface Interval will read ">24H".

If you see the image of a Diver-Down flag instead of a time value, this indicates that the latest dive reflects a duration which would carry that dive past the current time.

For example, if a diver creates a dive profile at 11:00 A.M with a duration of 30 minutes, and THEN goes in the water, the Diver-Down indicator will display until 11:30 at which point the current surface Interval value will begin to display and increment. This might be of use to a Divemaster who wishes to know when to expect a diver to return to the surface after a planned dive. It also serves as a reminder to prevent you from entering profiles which would overlap each other. In typical usage, you will never see this flag, since you probably won't be entering your dive entries until after each dive.

It is generally recognized that flying immediately after diving increases your risk of DCS. The current consensus is that at least 24 hours should elapse between your last dive and flying. This is based on numerous studies by various dive organizations. Even if you wait the recommended 24 hours, there is no guarantee that flying will not contribute to your risk of DCS. Generally speaking, longer is better.