It is an accidental error.

这是偶然的误差。

He discovered an accidental error in his composition.

他在作文中发现了一个意外的错误。

He discovered an accidental error in his composition.

他在作文里发现了一个意外的错误。

Accidental error check: To recognize the unusual conditions with the mathematical statistics theory.

随机误差校验：用数理统计理论对全面统计数据进行异常点识别。

How to avoid mistaken error and control accidental error and some suggestions to advance the testing precision of the windtunnel in different period are presented in the paper.

本文对如何避免过失误差，控制好偶然误差以提高风洞不同期试验精度提出了一些建议。