When do NAVTEX broadcasts typically achieve maximum transmitting range?

NAVTEX broadcasts typically achieve maximum transmitting range in the middle of the night due to the propagation characteristics of radio waves. During nighttime, the ionosphere's conditions are more favorable for long-distance transmission. The nighttime ionospheric layer can reflect radio waves back to the Earth's surface more effectively than during daylight hours. This is because solar radiation during the day can ionize the upper atmosphere, causing changes that can limit the range of radio signals.

In contrast, during the day, especially when the sun is high, the D layer of the ionosphere becomes more active and absorbs lower frequency signals, reducing their effective range. Therefore, radio communications, including NAVTEX broadcasts, are generally more reliable and can reach further around the clock when propagated during nighttime.