It's Always Best To Have A Run Kit For A Flight. 

Preparing for a business trip or vacation often means packing carefully and checking your list twice. We’ve retrieved expert advice from flight attendants regarding a simple trick many travelers overlook: a run kit. This bag keeps your most important items safe and within reach throughout your trip.

 A RUN-KIT is a small bag worn on your body to keep emergency essentials close when you need to move quickly and cannot reach the overhead bin. Commercial airplanes must be able to evacuate passengers in under 90 seconds, leaving no time to search for belongings. A sling or crossbody bag works best because it stays flat against your chest and is comfortable enough to wear while resting. Pack only the essentials: your passport, Real-ID, credit card, and cell phone. Everything else in your luggage can usually be replaced or purchased later with the card you kept safely on you.

Keeping your passport/Real-ID on your chest also makes airport arrivals easier. When you reach customs, you can pull it out right away instead of searching through your bags while others are unpacking on the airport floor.