Aeroflot Flight 1661
Antonov An-24B · Collision with weather balloon
From Novosibirsk Tolmachevo Airport (OVB) to Bratsk Airport (BTK)
Event
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- Event fatalities
- 45 · all aircraft and ground
- Ground fatalities
- Unknown
- Occupants
- 45
- Survivors
- 0
- InjuriesFatal: death within 30 days. Serious: over 48 hours in hospital within a week, most broken bones, severe bleeding, nerve or organ damage, or serious burns. Minor: anything less. Glossary
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- Airline
Antonov An-24B
- Aircraft type
- Antonov AN-24
- Category
- Airplane · from aircraft type
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- CCCP-47751
- Operator
- Aeroflot
- Onboard fatalities
- 45
- Route
- From Novosibirsk Tolmachevo Airport (OVB)To Bratsk Airport (BTK)
Cause areas
- Environmental issues › Physical environment
From the investigation findings the Wikipedia article reports, sorted into the NTSB's cause areas with AI assistance.
Approximate · Estimated position: Toguchin, near the place the Wikipedia article names. Not the accident site.
From the Wikipedia article
Aeroflot Flight 1661 was a passenger flight operated by an Antonov An-24 that crashed during its initial climb, 25 minutes after take-off from Tolmachevo Airport on 1 April 1970. All 45 people on board perished. An investigation revealed that the Antonov collided with a radiosonde, causing a loss of control.
Accident
Flight 1661 was a scheduled domestic flight from Novosibirsk to Bratsk, Russia, with an intermediate stop at Krasnoyarsk. At 03:42 local time the An-24 departed Tolmachevo Airport from runway 25 on a heading of 251°. Shortly after take-off, the aircraft made a turn to the left, and at 03:53 contacted air traffic control (ATC) and reported their altitude as 4,200 meters. They then received clearance to continue climbing to 6,000 meters. At 04:10 ATC attempted to contact flight 1661, but no further transmissions from the Antonov were received. The crashed aircraft was found in a field approximately 142 km from Tolmachevo Airport; there were no survivors. Among the victims were the members of a youth ice hockey team, who were flying to a game.
Investigation and cause
Investigation
Investigators examining the crash site discovered unusual damage to the aircraft's radome and nose structure, and noticed that a substantial portion of the windshield was missing. Also found among the wreckage were parts of two radiosondes of the type then being used by the Federal Service for Hydrometeorology and Environmental Monitoring for the monitoring of meteorological conditions. Investigators also discovered parts of the aircraft's nose cone six km away from the main crash site; these components displayed evidence of collision with a solid object. Officials concluded that the accident was caused by a collision in flight with a foreign object: the radiosonde/balloon assembly.
The investigation concluded that the aircraft's nose cone collided with a radiosonde, at a distance of 131 km from Tolmachevo, while ascending through 5,400 meters. The collision destroyed the aircraft's weather radar and damaged the cockpit. Out of control, the Antonov nosed over and began to descend rapidly. At an altitude of 2,000 meters and a speed of 700 km/h, the wing and horizontal stabilizer separated from the aircraft due to aerodynamic forces well beyond the plane's design limits. The fuselage then continued 2.5 km before striking the ground at 300 km/h and a vertical speed of 60 m/sec. The flight lasted 25 minutes, 25 seconds.
Text from the Wikipedia article “Aeroflot Flight 1661” (revision 1369761759, retrieved 2026-09-18) by its authors, under CC BY-SA 4.0. Extracted as plain text: references, tables, images and some sections are left out. Read the article
Sources
Wikipedia article: Aeroflot Flight 1661
- Article
- Aeroflot Flight 1661
- Revision
- 1369761759 · 2026-08-17 · retrieved 2026-09-18
- Wikidata
- Q16662379
- Licence
- Text CC BY-SA 4.0, by the article's authors; Wikidata CC0; town positions GeoNames (CC BY 4.0)
Where each value comes from
- Record
- Wikipedia article "Aeroflot Flight 1661" (page 57829312, revision 1369761759)
- Date
- Wikipedia infobox: date
- Place and country
- Wikipedia infobox: site
- Map position
- place the Wikipedia infobox site links (Wikidata coordinates)
- Aircraft, operator and route
- Wikipedia infobox: aircraft type, registration, operator, origin and destination; route airports from the linked airport articles' Wikidata codes (OurAirports)
- Operation
- flight number in the article title
- Fatalities
- Wikipedia infobox: aircraft fatalities
- Ground fatalities
- not stated in the Wikipedia infobox
- Summary
- Wikipedia infobox: summary
Source notes (1)
- Wikipedia · Facts from the Wikipedia article's infobox and coordinates, not checked against an investigation report. Independent review pending.