AirNav Ensures Flight Flows Are Not Disturbed By Semeru Activities

Illustration - a number of aircraft parked at Soekarno-Hatta International Airport, Tangerang, Banten. ANTARA/Azmi Samsul M

The Perum Institute for Indonesian Aviation Navigation Services (LPPNPI) or AirNav Indonesia ensures that flight flows at airports are not disturbed by the increase in the activity of Mount Semeru in Lumajang Regency, East Java.

"Until we published this information, the situation has not been in a condition that forces the closure of the airspace because of the threat of volcanic ash clouds," said AirNav Indonesia EVP of Corporate Secretary Hermana Soegijantoro in a written statement reported by ANTARA, Kams, November 20.

He explained, for now, flight routes, especially at airports around Malang, Banyuwangi, Surabaya and Yogyakarta, are all still running normally as usual.

"No airports have been closed and so far no flights have been canceled," he said.

Hermana emphasized that AirNav Indonesia continues to carry out intensive monitoring of flight routes and airports that have the potential to be affected, and consistently inform the latest developments through the issuance of ASHTAM.

"The last update is ASHTAM number VAWR6038 which we released through the International NOTAM Office AirNav Indonesia on November 20, 2025, at UTC (09.00 WIB)," he explained.

Based on the ASHTAM report, it is stated that the status of Mount Semeru is set with the status of the "Red Code", or which means that the eruption activity is quite significant and has the potential to disrupt flight routes.

Volcanic ash is observed to be at two different heights. At low levels, the ash distribution is on a surface of up to about FL150 (8:4,500 meters), moving southeast with wind speeds of about 5 knots.

Then, the ash distribution at a high level, is on the surface up to about FL450 (8:13,500 meters), moving to the southwest at a speed of about 15 knots.

"Our ASHTAM is released to all stakeholders who have an interest, both at home and abroad. The validity period is 24 hours, until there is further notification," he explained.

He explained that ASHTAM data containing technical information is an important reference for all aviation stakeholders in decision making regarding mitigation, adjusting flight routes, and regulating air traffic.

"This document was published as a flight safety warning because Semeru was observed still emitting volcanic ash," he said.

He explained that the information collected by NOTAM Office AirNav Indonesia from various sources included Himawari-8 satellite imagery, monitoring cameras, and data from the Center for Volcanology (PVMBG).

In the latest observation before ASHTAM was released, ash at high altitude was already difficult to see due to being covered by weather clouds, but the movement model showed the ash would weaken in the next few hours.

"Today, we are also collecting data from the results of a paper test conducted by PT Angkasa Pura Indonesia and the airport authority office (Otban) at nearest airports, such as Abdurrahman Saleh Airport (Malang), YIA and Adi Sucipto Airport (Yogjakarta) and AdiSumarmo Airport (Solo). Alhamdulillah, all the results are negative," he said.

As is known, the alert status of Mount Semeru is set at Level IV (Awas) by the Center for Volcanology and Geological Disaster Mitigation (PVMBG).

Responding to this, AirNav Indonesia periodically continues to update this information in real-time to pilots and airlines to ensure flight safety is maintained.

Airline updates are carried out when needed, according to the latest developments from the weather center of volcanic information and satellites.