ABC News’ Martha Raddatz ( @martharaddatz) and Kristina Wong ( @kristina_wong) report:

When Secretary of State Hillary Clinton arrived unannounced in Libya earlier this week  it took a military plane to get her there, the Boeing C-17 Globemaster III.

In this video , Clinton is seen reviewing briefing papers in a colorful shawl, with sunglasses in the bright and slightly chilly aircraft.

The aircraft is used to carry massive amounts of cargo — troops, food, supplies — all over the world, often on humanitarian relief missions. The inside of the aircraft can be configured any way suitable for the mission, and on this mission Clinton sat in a quartet of seats, with aide Huma Abedin next to her. Most of her staff was in a different section of seats, with press and security personnel on the sides.

Philippe I. Reines is a senior adviser to Secretary Clinton. (Photo: Martha Raddatz/ABC News)

This is only the second time she has used a C-17. The other instance was when she flew to Baghdad a couple of years ago.

In a reminder that the North African nation is still a war zone, the pilot of Clinton’s C-17 maneuvered a steep landing into Libya and a steep ascent out in order to minimize exposure of the aircraft to small arms and shoulder-fired surface-to-air missiles.

In Libya, this is more than a perfunctory threat. Shoulder-launched surface-to-air missiles, also known as MANPADS (man portable air defense systems) are particularly deadly in that they are cheap and very accurate, and very  easily accessible in Libya, according to ABC News consultant and former Marine Corps fighter pilot Steve Ganyard .

With the fall of the Gadhafi regime, ammunition storage facilities have been looted and thousands of MANPADS are now missing.  Most will show up on arms black markets around the world, making very sophisticated technology accessible to terrorists and insurgent groups, Ganyard said.

Coincidentally, Clinton is responsible for the U.S. government program that seeks to buy back MANPADS on the global black markets. This program spends tens of millions of dollars a year trying to buy up these dangerous weapons because of the great threat they pose to defenseless civilian airliners, said Ganyard, also a former deputy assistant secretary of state who worked on MANPAD issues.

“Terrorists have attempted to shoot down civilian airliners in the past, and the worry is that the Libyan MANPADS will flood the market, making it easier to for terrorists to carry out such a plan,” Ganyard said.

Ganyard added that on both the ascents and descents, any member of the crew not flying was looking out the windows so that if a MANPAD was shot at the aircraft, the pilots could make defensive maneuvers and shoot off hot decoy flares that are part of the aircraft’s defensive capabilities. That way, the MANPAD, which seeks out hot spots like the exhaust of aircraft engines, will be decoyed by the flares and turn away from the aircraft, its intended target.

Inside the cockpit of Secretary Clinton's C-17. (Photo: Martha Raddatz/ABC News)

The C-17 Clinton rode in belonged to McChord Air Field at Joint Base Lewis-McChord in Washington state, and members of the crew were from McChord’s 62nd Airlift Wing and the 446th Reserve Airlift Wing.

Busy looking for missiles, the crew remained professional and calm, yet nice.

“Ma’am, we’re going to be a bit busy during takeoff but will answer any questions you have after that,” a crew member told ABC News politely before takeoff.

Once the C-17 got above 20,000 feet, it was safe from surface-to-air missiles.

In the case of small arms fire, the aircraft is usually safe above a few thousand feet above the ground. However, small arms fire is almost impossible to see and so the best defense is to climb quickly in order to get out of range.

The C17 is cavernous. More than 55 feet tall and 174 feet long, the  four-engine, multi-service military-transport aircraft  can carry a cargo of wheeled U.S. Army vehicles in two side-by-side rows, including the U.S. Army’s main battle tank, the M-1, according to the manufacturer’s website . There is a ramp in the back, and windows — more like portholes — so high you can’t see out of them, making the bumpy ride a little disconcerting.

While there were few luxuries on board, there were, at least, two Porta-Johns.