Background: UFO are an English rock band that was formed in London in August 1969. They became a transitional group between early hard rock and heavy metal and the new wave of British heavy metal. The band's current lineup includes vocalist Phil Mogg, lead guitarist Vinnie Moore, bass guitarist Rob De Luca, keyboardist and rhythm guitarist Paul Raymond and drummer Andy Parker. They have gone through several line-up changes, leaving Mogg as the only constant member, and had two hiatuses (1983-1984 and again from 1989 to 1991).
Context: Tensions had begun to grow between Mogg and Schenker in the late 1970s, possibly from Schenker often leaving before or during shows. Soon after UFO's show in Palo Alto, California on 29 October 1978, Schenker left the band. He made a brief return to the Scorpions before going on to form his own Michael Schenker Group.  After Schenker's exit, UFO rehired Paul "Tonka" Chapman on guitar who brought over unused track ideas from Lone Star's drummer Dixie Lee. Shortly after, they released their next LP, No Place to Run in January, 1980. Produced by former Beatles producer George Martin, No Place To Run failed to match up to the success of its predecessors, though it fractionally missed the UK Top 10. Paul Raymond left the band at the end of the No Place To Run tour and was replaced by John Sloman from Uriah Heep for a couple of months and then by former Wild Horses guitarist and keyboardist Neil Carter, who helped fill the void in the songwriting left by Schenker's departure. Carter debuted with UFO on stage at the three-day Reading Festival on 23 August 1980, when the band played as the Saturday night headline act. At the beginning of the following year, UFO released the self-produced The Wild, the Willing and the Innocent, which had a lighter pop rock sound, which was popular at the time. The album achieved mild success in the UK, reaching the UK Top 20, and the single "Lonely Heart" was released.  In February 1982 the band released Mechanix. It was very successful in the UK, where it reached No.8, the band's highest ever placing. Later that year, founding member Pete Way left the band to form Fastway with Motorhead guitarist "Fast" Eddie Clarke and then his own band, Waysted. He was replaced by Talas bassist, Billy Sheehan. UFO released Making Contact in 1983, but the album was a critical and commercial failure. Thus, that March, UFO decided to disband. The band played a UK farewell tour with Paul Gray (ex Eddie and the Hot Rods and The Damned bassist). However, there was a hint that this might not be permanent, when UFO released a compilation album featuring songs by UFO (as well as other groups featuring ex-members of UFO) entitled Headstone, the sleeve of which showed a headstone, denoting UFO with their formation date but an incomplete end date.  This proved to be a short hiatus as, just short of two years later, in late 1984, Mogg assembled a new UFO line-up, featuring Paul Gray on bass again, ex-Diamond Head drummer Robbie France (replaced in 1985 by former Magnum drummer Jim Simpson), and Atomik Tommy M (Tommy McClendon), a former roadie who also wrote lyrics for Loudness, on guitar, with Paul Raymond rejoining shortly after and released Misdemeanor. This was followed by the 1988 EP Ain't Misbehavin. Despite the renewed activity of the band, neither release was financially successful and they officially disbanded again in 1989 after a string of guitarists replacing McClendon: Myke Gray of Jagged Edge in late 1987, in 1988 former Legs Diamond guitarist Rik Sanford and Tony Glidewell, while Pete Way rejoined on bass, and finally in 1989 future Cold Sweat guitarist Erik Gamans.
Question: What is Schenker?

Answer:
Tensions had begun to grow between Mogg and Schenker in the late 1970s, possibly from Schenker often leaving before or during shows.