go into a nosedive
go into a nosediveand take a nosedive
1. Lit. [for an airplane] suddenly to dive toward the ground, nose first. It was a bad day for flying, and I was afraid we'd go into a nosedive. The small plane took a nosedive. The pilot was able to bring it out at the last minute, so the plane didn't crash.
2. . Fig. [for someone] to fall to the ground face first. She took a nosedive and injured her face.
3. . Fig. to go into a rapid emotional or financial decline, or a decline in health. Our profits took a nosedive last year. After he broke his hip, Mr. Brown's health went into a nosedive, and he never recovered.
See also: nosedive